Search

The potential of blue light (BL) and sous-vide (S-V) as a novel approach for food preservation was investigated via measurements of the total phenolic content (TPC), antioxidative activity, color, and their antibacterial effect on Listeria monocytogenes in two versions of laboratory-prepared kale pesto, with and without the addition of turmeric. The TPC ranged from 85 to 208 mg/100 g GAE d.m. and 57 to 171 mg/100 g GAE d.m., respectively. In both versions, the highest TPC was in the blue light–sous-vide samples, while the lowest was after the sous-vide, with a loss of polyphenols of almost 40% during storage when turmeric was absent. Antioxidative capabilities of the pesto were initially estimated at 54.07 and 7.46 µmol TE/g d.m., respectively, indicating significant bioactivity enhancement by turmeric. In turmeric-enriched pesto, sous-vide decreased the antioxidative activity levels by 12% in fresh pesto and by 45% during storage. Meanwhile, blue light compensated for the losses caused by the sous-vide treatment. Although the hue angle (h°) of sous-vide pesto was lower than that of blue light pesto in most samples, sequential BL and S-V ultimately yielded the lowest h°. The sequential BL and S-V treatment resulted in a 1.7 log reduction in the L. monocytogenes population, whereas adding turmeric increased the treatment efficacy by another 2.0 logs. Thus, as a source of photosensitizing molecules, turmeric was highly antibacterial after photothermal activation with blue light and sous-vide. This study suggests that blue light could be an effective (pre)treatment used on pesto sauces to preserve bioactivity and to improve safety when enriched with a natural additive like turmeric. [ABSTRACT FROM AUTHOR]

Newly developed formulas of ready-to-eat (RTE) products, despite conforming to the latest nutritional trends involving low-processed and high-protein products, may pose a risk of promoting the growth of Listeria monocytogenes during shelf life. Food safety experts recommend challenge tests to assess the growth potential of L. monocytogenes, which will ultimately provide microbiological evidence to determine the food safety limit. The present study evaluated whether RTE uncured vacuum-packed pork bars with dried plasma met the 100 CFU/g safety level at the end of shelf life under certain storage conditions and aimed to develop predictive models for the growth of L. monocytogenes in the above product. The bars were artificially inoculated with a mixture of three strains of L. monocytogenes at two different inoculum densities of 2 log CFU/g and 5 log CFU/g and stored at three different temperatures (2, 4, and 6 °C) and then subjected to microbiological evaluation at specific time intervals up to 21 storage days. The growth potential (Δ-value) for RTE pork bars contaminated with 2 log CFU/g L. monocytogenes inoculum was 0.36, 0.14, and 0.91 log CFU/g at 2, 4, and 6 °C, respectively, while for bars contaminated with 5 log CFU/g inoculum, they were −0.36, −0.40, and 0.64 at 2, 4, and 6 °C, respectively. Statistically higher growth potential (p < 0.05) was detected for RTE bars contaminated with 2 log CFU/g inoculum than with 5 log CFU/g. The results indicate that this type of product must be classified as a food category: "Ready-to-eat foods able to support the growth of L. monocytogenes, other than those intended for infants and for special medical purposes" (Category 1.2. according to EU Regulation 2073/2005). The newly created models can also describe L. monocytogenes growth in an environment where factors, such as temperature, pH, and aw, change with time. The results showed that a higher inoculum density statistically reduced the growth potential values of L. monocytogenes compared to a lower density. [ABSTRACT FROM AUTHOR]

Biofilms are of great concern for the meat industry because, despite the implementation of control plans, they remain important hotspots of contamination by foodborne pathogens, highlighting the need to better understand the ecology of these microecosystems. The objective of this paper was to critically survey the recent scientific literature on microbial biofilms of importance for meat safety and quality, also pointing out the most promising methods to combat them. For this, the databases PubMed, Scopus, Science Direct, Web of Science, and Google Scholar were surveyed in a 10-year time frame (but preferably papers less than 5 years old) using selected keywords relevant for the microbiology of meats, especially considering bacteria that are tolerant to cleaning and sanitization processes. The literature findings showed that massive DNA sequencing has deeply impacted the knowledge on the species that co-habit biofilms with important foodborne pathogens (Listeria monocytogenes, Salmonella, pathogenic Escherichia coli, and Staphylococcus aureus). It is likely that recalcitrant commensal and/or spoilage microbiota somehow protect the more fastidious organisms from harsh conditions, in addition to harboring antimicrobial resistance genes. Among the members of background microbiota, Pseudomonas, Acinetobacter, and Enterobacteriales have been commonly found on food contact and non-food contact surfaces in meat processing plants, in addition to less common genera, such as Psychrobacter, Enhydrobacter, Brevundimonas, and Rothia, among others. It has been hypothesized that these rare taxa may represent a primary layer in microbial biofilms, offering better conditions for the adhesion of otherwise poor biofilm formers, especially considering their tolerance to cold conditions and sanitizers. Taking into consideration these findings, it is not only important to target the foodborne pathogens per se in cleaning and disinfection plans but the use of multiple hurdles is also recommended to dismantle the recalcitrant structures of biofilms. In this sense, the last part of this manuscript presents an updated overview of the antibiofilm methods available, with an emphasis on eco-friendly approaches. [ABSTRACT FROM AUTHOR]

Post-processing contamination of Listeria monocytogenes has remained a major concern for the safety of ready-to-eat (RTE) meat products that are not reheated before consumption. Mathematical models are rapid and cost-effective tools to predict pathogen behavior, product shelf life, and safety. The objective of this study was to develop and validate a comprehensive model to predict the Listeria growth rate in RTE meat products as a function of temperature, pH, water activity, nitrite, acetic, lactic, and propionic acids. The Listeria growth data in RTE food matrices, including RTE beef, pork, and poultry products (731 data sets), were collected from the literature and databases like ComBase. The growth parameters were estimated using the logistic-with-delay primary model. The good-quality growth rate data (n = 596, R2 > 0.9) were randomly divided into 80% training (n = 480) and 20% testing (n = 116) datasets. The training growth rates were used to develop a secondary gamma model, followed by validation in testing data. The growth model's performance was evaluated by comparing the predicted and observed growth rates. The goodness-of-fit parameter of the secondary model includes R2 of 0.86 and RMSE of 0.06 (μmax) during the development stage. During validation, the gamma model with interaction included an RMSE of 0.074 (μmax), bias, and accuracy factor of 0.95 and 1.50, respectively. Overall, about 81.03% of the relative errors (RE) of the model's predictions were within the acceptable simulation zone (RE ± 0.5 log CFU/h). In lag time model validation, predictions were 7% fail-dangerously biased, and the accuracy factor of 2.23 indicated that the lag time prediction is challenging. The model may be used to quantify the Listeria growth in naturally contaminated RTE meats. This model may be helpful in formulations, shelf-life assessment, and decision-making for the safety of RTE meat products. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is an important foodborne pathogen causing listeriosis. L. monocytogenes, existing in the natural environment, can also contaminate food products, which poses a serious threat to human health and life, especially for high-risk groups: pregnant women, newborn babies, and the elderly. Environmental adaptation of L. monocytogenes refers to the various strategies and mechanisms used by this bacterium to survive and thrive in diverse and often hostile environments that include, among others, toxic heavy metals and disinfectants. The aim of this study was to analyze WGS (whole-genome sequencing) data of 45 L. monocytogenes strains isolated from food to compare the prevalence and types of genetic determinants encoding resistance to toxic metals, such as arsenic and cadmium, as well as quaternary ammonium compounds, like benzalkonium chloride. In L. monocytogenes strains, resistance genes were detected for disinfectants, such as benzalkonium chloride (4.4%), as well as for toxic heavy metals, like cadmium (28.9%) and arsenic (24.4%). The bcrABC cassette was found together with the cadA2C2 genes in two strains: 3855-D (IIc, ST9, CC9) and 4315 (IVb, ST6, CC6). The arsenic cassette, encoded by the genes arsR1D2R2A2B1B2, was co-selected with the cadA4C4 genes. The arsenic cassette was prevalent in nine strains of clonal complex CC2 (82%), one strain of CC3 (9%), and one strain of CC11 (9%). In contrast, the benzalkonium chloride cassette was detected in one strain of CC6 and one strain of CC9. The results of the present study demonstrate the need for further research into the characteristics of L. monocytogenes isolated from other sources in order to understand their spread throughout the food chain. [ABSTRACT FROM AUTHOR]

Foodborne pathogens are microorganisms that cause illness through contamination, presenting significant risks to public health and food safety. This review explores the metabolites produced by these pathogens, including toxins and secondary metabolites, and their implications for human health, particularly concerning cancer risk. We examine various pathogens such as Salmonella sp., Campylobacter sp., Escherichia coli, and Listeria monocytogenes, detailing the specific metabolites of concern and their carcinogenic mechanisms. This study discusses analytical techniques for detecting these metabolites, such as chromatography, spectrometry, and immunoassays, along with the challenges associated with their detection. This study covers effective control strategies, including food processing techniques, sanitation practices, regulatory measures, and emerging technologies in pathogen control. This manuscript considers the broader public health implications of pathogen metabolites, highlighting the importance of robust health policies, public awareness, and education. This review identifies research gaps and innovative approaches, recommending advancements in detection methods, preventive strategies, and policy improvements to better manage the risks associated with foodborne pathogens and their metabolites. [ABSTRACT FROM AUTHOR]

This study introduces a quantitative risk assessment (QRA) model aimed at evaluating the risk of invasive listeriosis linked to the consumption of ready-to-eat (RTE) smoked and gravad fish. The QRA model, based on published data, simulates the production process from fish harvest through to consumer intake, specifically focusing on smoked brine-injected, smoked dry-salted, and gravad fish. In a reference scenario, model predictions reveal substantial probabilities of lot and pack contamination at the end of processing (38.7% and 8.14% for smoked brined fish, 34.4% and 6.49% for smoked dry-salted fish, and 52.2% and 11.1% for gravad fish), although the concentrations of L. monocytogenes are very low, with virtually no packs exceeding 10 CFU/g at the point of sale. The risk of listeriosis for an elderly consumer per serving is also quantified. The lot-level mean risk of listeriosis per serving in the elderly population was 9.751 × 10−8 for smoked brined fish, 9.634 × 10−8 for smoked dry-salted fish, and 2.086 × 10−7 for gravad fish. Risk reduction strategies were then analyzed, indicating that the application of protective cultures and maintaining lower cold storage temperatures significantly mitigate listeriosis risk compared to reducing incoming fish lot contamination. The model also addresses the effectiveness of control measures during processing, such as minimizing cross-contamination. The comprehensive QRA model has been made available as a fully documented qraLm R package. This facilitates its adaptation for risk assessment of other RTE seafood, making it a valuable tool for public health officials to evaluate and manage food safety risks more effectively. [ABSTRACT FROM AUTHOR]

In recent years, plant essential oils have been confirmed as natural inhibitors of foodborne pathogens. Citrus reticulata Blanco cv. Tankan peel essential oil (CPEO) showed anti-Listeria monocytogenes (LM) activities, and this study investigated the associated mechanisms by using high-resolution electron microscope, fluorescence spectrometer, flow cytometer, potentiometer, and transcriptome sequencing. The results showed that CPEO restrained LM growth at a minimum inhibitory concentration of 2% (v/v). The anti-LM abilities of CPEO were achieved by disrupting the permeability of the cell wall, damaging the permeability, fluidity, and integrity of the cell membrane, disturbing the membrane hydrophobic core, and destroying the membrane protein conformation. Moreover, CPEO could significantly inhibit the LM aggregation from forming biofilm by reducing the extracellular polymeric substances' (protein, polysaccharide, and eDNA) production and bacterial surface charge numbers. The RNA sequencing data indicated that LM genes involved in cell wall and membrane biosynthesis, DNA replication and repair, quorum sensing and two-component systems were expressed differently after CPEO treatment. These results suggested that CPEO could be used as a novel anti-LM agent and green preservative in the food sector. Further studies are needed to verify the anti-LM activities of CPEO in real food. [ABSTRACT FROM AUTHOR]

A total of 104 samples of chicken meat acquired on the day of slaughter from two slaughterhouses in northwestern Spain were analyzed. These comprised 26 carcasses and 26 cuts from each of the two establishments. An average load of 5.39 ± 0.61 log10 cfu/g (total aerobic counts) and 4.90 ± 0.40 log10 cfu/g (psychrotrophic microorganisms) were obtained, with differences (p < 0.05) between types of samples and between slaughterhouses. Culturing methods involving isolation based on the UNE-EN-ISO 11290-1:2018 norm and identification of isolates by polymerase chain reaction (PCR) to detect the lmo1030 gene allowed the detection of Listeria monocytogenes in 75 samples (72.1% of the total; 50.0% of the carcasses and 94.2% of the cuts). The 75 isolates, one for each positive sample, were tested for resistance against a panel of 15 antibiotics of clinical interest by the disc diffusion method. All isolates belonged to the serogroup IIa (multiplex PCR assay) and showed resistance to between four and ten antibiotics, with an average value of 5.7 ± 2.0 resistances per isolate, this rising to 7.0 ± 2.1 when strains with resistance and reduced susceptibility were taken together. A high prevalence of resistance was observed for antibiotics belonging to the cephalosporin and quinolone families. However, the level of resistance was low for antibiotics commonly used to treat listeriosis (e.g., ampicillin or gentamicin). Nine different resistance patterns were noted. One isolate with each resistance pattern was tested for its ability to form biofilms on polystyrene during 72 h at 12 °C. The total biovolume of the biofilms registered through confocal laser scanning microscopy (CLSM) in the observation field of 16,078.24 μm2 ranged between 13,967.7 ± 9065.0 μm3 and 33,478.0 ± 23,874.1 μm3, and the biovolume of inactivated bacteria between 0.5 ± 0.4 μm3 and 179.1 ± 327.6 μm3. A direct relationship between the level of resistance to antibiotics and the ability of L. monocytogenes strains to form biofilms is suggested. [ABSTRACT FROM AUTHOR]

The transition towards more sustainable packaging calls for improving our ability to predict, control, and inhibit microbial growth. Despite the importance of modified atmosphere packaging (MAP) in food preservation, the exact relations between MAP gases (CO2, O2, N2) and microbial behavior are still poorly understood. Addressing this major knowledge gap requires a specific infrastructure to gain precise control over the gas composition during storage time. Thus, this study aimed at developing and validating an innovative gas-washing bottle incubation system (GBIS) with an adapted pH methodology for monitoring microbial growth in liquid media under different well-controlled conditions. Listeria monocytogenes—a psychrotrophic pathogen raising severe safety concerns under refrigerated conditions—was used as a representative microorganism. The results showed that daily gas flushing effectively dominated overnight headspace variations, allowing incubating L. monocytogenes and daily sampling for 13 days under static conditions. Subsequently, storage experiments were performed at 4 °C under stable pH and anaerobic conditions with different CO2 levels (20–40–60%). Significant growth reduction was observed from 6.0 to 4.8 log CFU/mL as CO2 increased from 20% (pH = 6.7) to 60% (pH = 6.2) (p ≤ 0.05). Overall, GBIS shows great potential in data collection for predictive modeling and, consecutively, for boosting decision-making in the food packaging sector. [ABSTRACT FROM AUTHOR]

In this study, for the first time, the volatile fraction from two domesticated Capsicum annuum accessions ("Paprika" and "Baklouti") collected in Tunisia was investigated by two complementary analytical techniques, such as Solid-Phase Microextraction–Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and Proton Transfer Reaction–Time-of-Flight–Mass Spectrometry (PTR-ToF-MS). The obtained results highlighted the presence of a high number of Volatile Organic Compounds (VOCs), including monoterpene and sesquiterpene compounds with α-curcumene, I-zingiberene, β-bisabolene and β-sesquiphellandrene as the major components. In addition, GC/MS was used to investigate the non-volatile chemical composition of the dried powders and their extracts, which were found to be rich in sulfur compounds, fatty acids and sugars. Eleven bacterial strains were chosen to assess the antimicrobial effectiveness of the extracts. The results showed that the extracts exhibited strain-dependent behavior, and the type strains displayed a greater susceptibility to the treatments, if compared to the wild strains, and, in particular, showed the best antimicrobial activity against Gram-positive bacteria, such as Listeria monocytogenes and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes biofilm contamination on food contact surfaces is a major concern for the food industry. Nanoparticle encapsulation appears as a novel strategy for food surface disinfection to prevent biofilm formation. Chitosan nanoparticles loaded with nisin and DNase I (DNase-CS-N) have been constructed to exhibit antimicrobial activity against L. monocytogenes. This study aimed to investigate their ability to inhibit L. monocytogenes biofilm formation and eliminate preformed biofilms on food contact surfaces (polystyrene, polyurethane, and stainless steel). DNase-CS-N could decrease 99% and 99.5% biofilm cell numbers at 1/2 MIC and MIC, respectively. At sub-MICs, DNase-CS-N could reduce cell motility (swimming and swarming) and slime production of L. monocytogenes. In terms of effect on biofilm elimination, DNase-CS-N at the concentration of 4 MIC led to 3–4 log reduction in biofilm cells in preformed biofilms, performing higher efficiency compared with other treatments (CSNPs, CS-N). Furthermore, the three-dimensional structure of L. monocytogenes biofilms was severely disrupted after DNase-CS-N treatment, with bacterial cells scattered on the surface. The morphology of biofilm cells was also greatly damaged with wrinkled surfaces, disrupted cell membranes, and leakage of intracellular nucleic acids and proteins. These results indicate the potential applicability of DNase-CS-N for inhibiting and eliminating L. monocytogenes biofilms on food contact surfaces. [ABSTRACT FROM AUTHOR]

Background/Objectives: Listeria monocytogenes is a foodborne pathogen that can infect both humans and animals and cause noninvasive gastrointestinal listeriosis or invasive listeriosis. The objectives of this study were to determine the genetic diversity of L. monocytogenes; the genes associated with its resistance to antibiotics, benzalkonium chloride (BC), and cadmium chloride (CdCl2); and its biofilm formation. Methods: A total of 132 fresh fruits (44 samples) and vegetables (88 samples) were selected for this study. The genetic diversity of the isolates and the genes associated with their antibiotic resistance were determined using PCR amplification; meanwhile, their levels of susceptibility to antibiotics were determined using the agar diffusion method. Their levels of resistance to BC and CdCl2 were determined using the minimum inhibitory concentration method, and their capacity for biofilm formation was evaluated using the crystal violet staining method. Results: A total of 17 L. monocytogenes strains were collected: 12.8% (17/132) from fresh fruits and vegetables in this study. The isolates of L. monocytogenes belonged to phylogenetic groups I.1 (29.4% (5/17); serotype 1/2a) and II.2 (70.5% (12/17); serotype 1/2b); strains containing Listeria pathogenicity islands (LIPIs) were also identified at prevalence rates of 100% for LIPI-1 and LIPI-2 (17/17), 29.4% for LIPI-3 (5/17), and 11.7% for LIPI-4 (2/17). The antibiotic susceptibility tests showed that the L. monocytogenes isolates exhibited six different multiresistant patterns, with multiple antibiotic resistance (MAR) index of ≥0.46 (70.5%; 12/17); additionally, the genes Ide, tetM, and msrA, associated with efflux pump Lde, tetracycline, and ciprofloxacin resistance, were detected at 52.9% (9/17), 29.4% (5/17), and 17.6% (3/17), respectively. The phenotypic tests showed that 58.8% (10/17) of cadmium-resistant L. monocytogenes isolates had a co-resistance of 23.5% (4/17) to BC. Finally, all strains of L. monocytogenes exhibited moderate biofilm production. Conclusions: The results of this study contribute to our understanding of the persistence and genetic diversity of L. monocytogenes strains isolated from fresh fruits and vegetables; in addition, their resistance to CdCl2, which is correlated with co-resistance to BC disinfectant, is helpful for the food industry. [ABSTRACT FROM AUTHOR]

Previous investigations have explored the involvement of wolves in parasitic and viral diseases, but data on the zoonotic bacteria are limited. The aim of this study was to assess the occurrence of bacterial zoonotic agents in 16 wolf (Canis lupus italicus) fecal samples collected in a protected area in Central Italy. Campylobacter spp., Salmonella spp., Yersinia spp., Listeria monocytogenes, and Shiga Toxin-Producing Escherichia coli (STEC) were investigated by culture, while polymerase chain reaction (PCR) was employed to detect Coxiella burnetii, Mycobacterium spp., Brucella spp., and Francisella tularensis. The presence of Extended Spectrum β-Lactamase (ESBL)- and carbapenemase-producing Enterobacteriaceae was also evaluated, using selective isolation media and detection of antimicrobial resistance genes. All samples were negative for Campylobacter spp., Salmonella spp., C. burnetii, Mycobacterium spp., Brucella spp., F. tularensis, and carbapenemase-producing Enterobacteriaceae. One sample tested positive for Yersinia aldovae and three for Yersinia enterocolitica BT1A. One L. monocytogenes (serogroup IIa) and one STEC, carrying the stx1 gene, were isolated. Two ESBL isolates were detected: one Serratia fonticola, carrying blaFONA-3/6 gene, and one Escherichia coli, carrying blaCTX-M-1 gene. Both ESBL isolates were resistant to different antimicrobials and therefore classified as multi-drug-resistant. Our data suggest that wolves are potential carriers of zoonotic bacteria and may contribute to the environmental contamination through their feces. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes causes listeriosis, a serious foodborne illness with a high mortality rate, especially in vulnerable populations. It accounts for 19% of foodborne deaths, with invasive cases having a mortality rate of up to 44%, leading to conditions like meningitis, bacteremia, and meningoencephalitis. However, the prognostic factors remain unclear. This study examines the hospital outcomes of invasive listeriosis and identifies risk factors for in-hospital and one-year mortality. We analyzed the electronic medical records of 118 hospitalized patients with non-perinatal, culture-proven invasive listeriosis collected over a 21-year period. The in-hospital mortality rate was 36.4%, with only 33.1% surviving one year and 22.0% surviving two years. The key findings indicate that a quick Sequential Organ Failure Assessment (qSOFA) score of ≥2 (OR 106.59, p < 0.001), respiratory failure (OR 7.58, p = 0.031), and shorter ampicillin duration (OR 0.53, p = 0.012) independently predicted poorer in-hospital outcomes. Additionally, a qSOFA score of ≥2 (OR 8.46, p < 0.001) and shorter ampicillin duration (OR 0.65, p < 0.001) were linked to higher one-year mortality. This study is the first to identify a qSOFA score of ≥2 as a significant marker for high-risk invasive listeriosis patients, with poorer outcomes linked to a qSOFA score of ≥2, respiratory failure, and shorter ampicillin use. [ABSTRACT FROM AUTHOR]

Background: Listeria monocytogenes, a Gram-positive intracellular bacillus, causes listeriosis, which is primarily transmitted through contaminated food and vertical transmission. The incidence of the disease is estimated to be between one and ten cases per million globally, with pregnant women being particularly vulnerable. Objective: The aim was to describe the clinical characteristics, management, and outcomes of cases of gestational listeriosis at Hospital Materno Infantil de Málaga in order to improve our understanding, diagnosis, and treatment of this disease. Methods: A retrospective analysis of six confirmed cases of listeriosis was performed in pregnant women or neonates. Diagnostic confirmation was achieved using analytic and microbiological methodologies, including blood cultures and the measurement of C-reactive protein (CRP). Ethical approval was obtained, and clinical data were reviewed for reasons related to consultation, treatment approaches, and complications. Results: The most frequently observed symptoms were fever and abdominal pain, with complications such as intrauterine death and suspected chorioamnionitis. Four patients were treated with antibiotics, leading to improved outcomes. No severe complications such as neurolisteriosis were observed. Conclusions: Pregnant women are more susceptible to L. monocytogenes, which can cause mild maternal symptoms but severe foetal outcomes, including prematurity, foetal death, or neonatal infections. Early diagnosis and prompt treatment are crucial for improving maternal–foetal outcomes. [ABSTRACT FROM AUTHOR]

Canada is a leading producer of wild lowbush blueberries, most of which are mechanically harvested, washed, individually quick frozen (IQF), and bulk packaged. Still, some berries are harvested by more gentle methods and sold as fresh-packed products. These berries do not undergo a wash step, nor are subjected to antimicrobial treatments. The purpose of this study was to conduct a microbiological survey of berries harvested in the province of Nova Scotia to assess their potential for harborage of bacterial foodborne pathogens. A combination of standardized plate count methods and 3M-Petrifilm protocols were used to enumerate total aerobic mesophilic bacteria (APC), yeasts and molds (YMC), coliforms, and generic E. coli, the latter being an indicator of fecal contamination. Overall, APC and YMC levels were 1.2 and 0.5 log greater, respectively, for berries collected early in the harvest season versus those acquired late season and varied significantly (p < 0.05) between farm (location) and harvest practices used. Berries harvested by our team using sanitized hand rakes (SH) had consistently lower APC and YMC levels than those harvested by farm crews. Yet, when gentle harvesting (GH) methods (hand-raking, walk-behind or modified mechanical harvesters) were employed on farms, lower numbers were generally observed compared to berries harvested by traditional tractor-mounted mechanized harvesters (MH). The presence of coliforms (and their levels) was also impacted by the harvest method, with detection rates of ~29%, 73%, and 92% in SH, GH, and MH samples, respectively. Mean counts were < 2.5 log10 CFU/g for both SH and GH berries, but significantly higher (p < 0.05) on MH berries (3.6 log10 CFU/g). Although ~56% of all berry samples collected (n = 350) contained coliforms, only 12 were positive for E. coli, 9 of which were MH samples. Only the latter had numbers > 2 log10 CFU/g, but none tested positive for Shiga toxin-producing serotype O157 (STEC O157) or Salmonella spp. when using internationally recognized selective enrichment and plating methods. ATP luminescence was used to assess the general hygiene of processing lines, whereby "hot spots" for microbial activity were identified, even after cleaning., Standard selective enrichment and plating methods were used for the detection of Listeria monocytogenes on 61 swab samples taken from berry totes or conveyor belts at different times during processing; 4 swabs tested positive for L. monocytogenes. However, the pathogen could not be detected by direct plating on selective agar without prior enrichment; this indicated its numbers were low. The results from this work demonstrated that alternative gentle harvest methods can reduce microbial numbers on wild blueberries. Although the frequency of fecal contamination in berry samples appeared to be low and targeted human pathogens were not detected; this represents a single study conducted over one harvest season. Therefore, it would be prudent for processors to seek effective antimicrobial technologies prior to packaging, while consumers should use caution and thoroughly wash produce before consumption. Where sporadic detection of L. monocytogenes was observed on environmental samples from the processing line, processors must ensure that effective sanitation programs are implemented to avoid potential food safety risks. [ABSTRACT FROM AUTHOR]

The rising prevalence of pathogenic bacteria in livestock meat poses a growing public health concern in China. The determination of antimicrobial resistance (AMR) is critical for the clinical management of foodborne infections stemming from livestock meat consumption. This study aimed to assess the prevalence of pathogenic bacteria in livestock meat (pork, beef, and mutton) sampled in China in 2021 and to identify the most common AMR patterns among the isolated pathogens. A total of 2515 raw livestock meat samples were collected across 15 provinces in China during 2021. Pathogen detection, including Listeria monocytogenes, Salmonella, and diarrheagenic Escherichia coli (DEC), followed China's national food safety standards. All Salmonella isolates underwent serotyping via slide agglutination. Antimicrobial susceptibility of Salmonella and DEC isolates was assessed using the broth dilution method. The detection rates for L. monocytogenes, Salmonella, and DEC in raw livestock meat were 9.06% (228/2, 515), 10.54% (265/2, 515), and 6.16% (155/2, 515), respectively. Pork showed the highest contamination rates for Salmonella and DEC, with prevalence rates of 17.60% (214/1, 216, χ2 = 124.62, p < 0.05) and 7.89% (96/1, 216, χ2 = 14.466, p < 0.05), respectively. L. monocytogenes contamination was notably higher in chilled (14.43%, 84/582) and frozen (12.39%, 55/444) meat than in fresh meat (χ2 = 43.510, p < 0.05). In contrast, Salmonella (12.09%, 180/1489, χ2 = 15.173, p < 0.05) and DEC (7.25%, 108/1489, χ2 = 12.275, p < 0.05) were more prevalent in fresh meat than in chilled or frozen samples. The predominant Salmonella serotypes identified were Salmonella enterica subsp. enterica serovar Typhimurium, followed by Salmonella enterica serovar Derby, Salmonella enterica serovar Rissen, Salmonella enterica serovar London, and Salmonella enterica serotype Enteritidis. Enteroaggregative E. coli was the most frequent pathotype among DEC (84.7%, 133/157), followed by enteropathogenic E. coli (8.3%, 13/157) and enterohemorrhagic E. coli (5.1%, 8/157). Among the 14 tested antimicrobial agents, Salmonella isolates demonstrated an overall resistance rate of 87.50%, while DEC exhibited a resistance rate of 84.70%. Ampicillin and tetracycline showed the highest resistance rates in both pathogens. Multi-drug resistance (MDR) was observed in 67.53% of Salmonella isolates (183 isolates) and 57.96% of DEC isolates (91 isolates). This study highlights the significant contamination of retail raw livestock meat in China by L. monocytogenes, Salmonella, and DEC. The high resistance of MDR in both pathogens poses serious public health risks. Chinese food safety and veterinary authorities should implement stricter measures to control pathogen contamination and regulate the use of antimicrobials in livestock to mitigate these risks. [ABSTRACT FROM AUTHOR]

This study investigates seasonal biomass variations in Betaphycus gelatinus, a red alga cultivated in the field in Ninh Thuan, Vietnam, along with the chemical composition, structural properties, and bioactivity of its carrageenan. Monthly measurements over a one-year period revealed peak growth (2.02% per day) and carrageenan yield (59.61%) in June, identifying it as the optimal harvest period. FTIR and NMR analyses of carrageenan extracted from field-cultivated B. gelatinus showed hybrid κ- and β-carrageenan forms and a unique pyruvylated β-carrageenan structure not previously reported for this species. Bioactivity assays indicated high antioxidant potential, with a total antioxidant capacity equivalent to 48.30 mg ascorbic acid/g carrageenan and an ABTS radical scavenging IC50 of 3.64 µg/mL. Additionally, antibacterial tests demonstrated strong inhibition of Listeria monocytogenes (12.00 mm inhibition zone). These findings suggest that field cultivation is a sustainable approach for carrageenan production, yielding bioactive compounds with promising applications in pharmaceuticals, cosmetics, and food preservation as a viable alternative to wild harvesting. [ABSTRACT FROM AUTHOR]

The consumption of organic food has increased in recent years. In organic rearing animals are exposed to outdoor conditions, which may increase their risk of infection from various pathogens. In the present study the occurrence of the most significant foodborne pathogenic bacteria in organic meat and ready-to-eat organic meat products was assessed. Out of 100 raw organic meat samples tested, 72 were contaminated with bacterial pathogens. The highest percentage of contaminated samples was observed in poultry meat (92.5%) followed by pork meat (66.7%). Furthermore, 50.0% of beef origin samples were positive for the bacteria tested. L. monocytogenes was found in 39.0% of samples, S. aureus was identified in 37.0%, Campylobacter in 20.0%, Salmonella in 8.0% and Shigatoxin-producing E. coli in 4.0% of raw meat samples. In 31.0% of samples a co-occurrence of two (83.9%) or three (16.1%) pathogens was observed. Among 100 samples of organic meat products tested, only L. monocytogenes was found in 5.0% of samples. The result of the present study indicated that organic food may be a source of harmful microorganisms that may pose foodborne infections to consumers. [ABSTRACT FROM AUTHOR]

The European Union (EU) regulations mandate 10% of all food packaging to be reusable by 2030. United States (U.S.) exporters of specialty crops face new challenges in ensuring microbiological food safety using reusable packaging. A novel antimicrobial formulation consisting of ammonium carboxylate salt of capric acid and L-arginine (GS-2) was recently developed as a spray coating chemical for food packaging materials. In this study, we evaluated the antimicrobial efficacy of GS-2 against microbial strains representing three foodborne bacterial pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica), one fungal spoilage organism (Aspergillus niger), and one surrogate viral pathogen (murine norovirus) on three reusable plastic materials (acrylonitrile butadiene styrene, high-density polyethylene, and polypropylene) and one cardboard packaging material, respectively. Different chemical concentrations, exposure times, and storage conditions were individually evaluated for the relative antimicrobial efficacies of GS-2 against these microorganisms. Our results showed that GS-2 was highly effective for inactivating bacterial pathogens on both plastic and cardboard surfaces. For instance, 3% GS-2 achieved a >5 log CFU/in2 reduction in E. coli O157:H7, L. monocytogenes, and S. enterica on tested plastic surfaces at an exposure time of 60 min. However, its efficacy against A. niger and murine norovirus was less optimal, resulting in a ≤1 log CFU/in2 reduction on all tested surfaces. Based on our study, GS-2 demonstrated a strong potential as an antibacterial coating reagent for reusable food packaging materials to minimize pathogen contamination and ensure the safety of the specialty crops. [ABSTRACT FROM AUTHOR]

Recent foodborne outbreaks and recalls involving Listeria monocytogenes and Salmonella-contaminated peaches have caused significant economic losses to the peach industry. This study evaluated the effectiveness of chlorine, a commonly used sanitizer in the fresh produce industry, against L. monocytogenes and Salmonella and its ability to control cross-contamination in fresh peaches. Peaches inoculated with L. monocytogenes or Salmonella (~6 log10 CFU/peach) were treated with 50–150 mg/L of free chlorine (FC, pH6.8) 24 h post-inoculation. The results revealed that chlorine had similar efficacy against L. monocytogenes and Salmonella on peaches (p > 0.05). A 30 s treatment at 50, 100, and 150 mg/L FC resulted in dose-dependent reductions (p < 0.05), achieving reductions of 0.88–0.92, 1.54–1.61, and 1.73–1.79 log10 CFU/peach, respectively. Extending the contact time to 2 min slightly but significantly enhanced the chlorine efficacy (p < 0.05). Additionally, a 30 s to 2 min exposure to chlorine with 50–150 mg/L FC resulted in a 1.05–1.43 log10 CFU/peach reduction in yeasts and molds. Tap water exposure led to substantial cross-contamination between inoculated and uninoculated fruits and processed water, with Salmonella exhibiting higher transfer rates than L. monocytogenes. The application of chlorine mitigated the cross-contamination of both pathogens but did not entirely prevent it. These findings offer valuable insights for the peach and other stone fruit industries to verify process controls. [ABSTRACT FROM AUTHOR]

High-pressure processing (HPP) is a promising technology for increasing the shelf life of food, with minimal effects on the nutritional or sensory quality. However, there has been a concern that high-oil-content foods may protect food pathogens in HPP, and that HPP can affect the quality of lipids. We inoculated Listeria monocytogenes and Salmonella Typhimurium into 34% and 54% oil-content pesto sauce, processed them either with HPP (600 MPa, 4 min) or thermal processing (82 °C, 5 min), and analyzed bacteria counts, pH, GC-MS (Terpene compounds), the time–kill kinetic study, and lipid oxidation value for 60 days in refrigerating storage (5 ± 2 °C). Our findings show that HPP significantly reduced the number of bacteria (more than 4-log) compared to thermal processing or non-processing. Additionally, we discovered terpene compounds (highest-level terpene: L-linalool, eugenol, and 1,8-cineol) in pesto oil that exhibit antimicrobial activity. Different oil content did not have any significant effect on bacteria levels. Regarding chemical results, all samples were of acceptable quality, and the processes did not show any negative effect on lipid oxidation (Peroxide and P-Anisidine value under 10 meq per kilogram of oil). In conclusion, our study indicates that HPP is a suitable method for high-oil-content pesto sauce. In addition, functional compounds naturally present in pesto may contribute to maintaining its microbial and chemical quality. [ABSTRACT FROM AUTHOR]

In recent years, the awareness of healthier lifestyles among consumers has driven to an increased interest in more natural, nutritious, and low-processed foods. Ferulic acid, one of the most abundant phenolic acids in plants, has demonstrated a wide spectrum of antimicrobial activities and a range of biomedical effects, including antioxidant, antiallergic, hepatoprotective, anticarcinogenic, anti-inflammatory, and antithrombotic, among others. The objective of this work was to study the antilisterial effect of ferulic acid (FA, 1500 mg/L) on fresh, ready-to-eat orange (FOJ) and apple (FAJ) juices and evaluate its effect on product quality. The results showed that FA reduced the Listeria monocytogenes population after 9 days of storage at 4 °C, but no effect on the indigenous microbiota was observed. The titratable acidity and color significantly changed. The antioxidant capacity and total phenolic content significantly increased with the addition of FA, being at least two times greater in fortified juices. FAJ and FOJ containing FA were scored lower (6.8 and 5.7 on a 9-point hedonic scale, respectively) than their respective controls. Overall, our results demonstrated that FA treatment could be a useful strategy to maintain the safety of fresh apple and orange juices and increase the antioxidant activity and phenolic content. The potential industrial applications and health benefits of the fortification of fruit juices with FA should be further explored. [ABSTRACT FROM AUTHOR]

Infective endocarditis (IE) is a disease associated with significant morbidity and mortality. It is more commonly caused by Gram-positive cocci, but Gram-positive bacilli may seldom cause the disease. Listeria monocytogenes is an aerobic Gram-positive coccobacillus and a foodborne and opportunistic pathogen most commonly causing gastrointestinal infections, even though bacteremia, sepsis, meningitis, and fetal infections may also occur. Listeria IE has rarely been described, with most reports being case reports or case series. Thus, the characteristics of this disease remain largely unknown. This systematic review aimed to present all published Listeria IE studies and describe their characteristics. A search of PubMed, Scopus, and the Cochrane Library for studies providing information on epidemiology, clinical findings, treatment, and outcome of Listeria IE cases was performed. A total of 54 studies containing data from 62 patients were included. Among all patients, 64.5% were male; the median age was 69 years. Among all patients, 54.8% had a history of a prosthetic valve. The aortic valve was the most commonly affected, followed by the mitral. Fever, heart failure, and embolic phenomena were the most commonly encountered clinical findings. The only isolated species was L. monocytogenes. Antimicrobial resistance was relatively low for aminopenicillins and aminoglycosides, the most commonly used antimicrobials for treating L. monocytogenes IE. Surgery was performed in 27.4% of patients. Mortality was 37.1%. Patients who survived were more likely to have had a prosthetic valve, to have necessitated transesophageal echocardiography for the diagnosis, to have mitral valve IE, and to have had surgical management; however, no factor was identified in a multivariate logistic regression model as an independent factor for overall mortality. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a Gram-positive bacterium that causes listeriosis, a severe foodborne illness that is particularly dangerous during pregnancy. It thrives in diverse environments, including refrigerated conditions and food production facilities, due to its adaptability to varying temperatures, pH levels, and salt concentrations. Its virulence stems from the ability to invade host cells, particularly macrophages and epithelial cells, and avoid, or at least postpone, immune detection by utilizing virulence factors such as internalins, listeriolysin O, and actin assembly-inducing protein. This intracellular motility and biofilm formation make LM a persistent pathogen in food safety and public health. Pregnant women are at a much higher risk of listeriosis, which can result in serious fetal complications such as miscarriage, stillbirth, and preterm labor due to LM's affinity for placental tissues. The vertical transmission of LM from mother to fetus can lead to neonatal listeriosis, which can result in sepsis and meningitis, with high mortality rates if not promptly treated. Early diagnosis and treatment with antibiotics, such as ampicillin or gentamicin, are crucial for maternal and neonatal outcomes. [ABSTRACT FROM AUTHOR]

Bacterial resistance and persistence in food environments are major concerns for the industry, which constantly seeks new strategies to reduce microbial contamination. Rhamnolipids (RL) biosurfactants are considered sustainable and green alternatives to synthetics; furthermore, they have demonstrated potential for controlling various foodborne pathogens. Food environments are typically exposed to diverse pH, solutes, temperatures, and water activity (aw) levels that may favor the survival of pathogens. Therefore, it is crucial to consider these factors in evaluating the performance of novel antimicrobials. Our study examined the influence of pH and sucrose on the antimicrobial activity of RL against both planktonic and biofilm of Listeria monocytogenes. We found that the presence of sucrose can enhance the antimicrobial effectiveness of RL against both planktonic and sessile bacteria. The addition of sugar particularly improved RL action at pH 6 and 7. Moreover, we observed that the type and size of RL self-assembly structures depend on the pH and sucrose concentration. These findings suggest potential for developing RL-based innovative methods to control L. monocytogenes in sugar-rich or -low aw foods and environments. [ABSTRACT FROM AUTHOR]

Listeriosis is a dangerous zoonosis caused by bacteria of the genus Listeria, with Listeria monocytogenes (LM) being the most pathogenic species. Listeria monocytogenes has been detected in various animal species and in humans, and its ability to evolve from an environmental saprophyte to a powerful intracellular pathogen is driven by the invasion mechanisms and virulence factors that enable cell invasion, replication and cell-to-cell spread. Key regulatory systems, including positive regulatory factor A (PrfA) and the stress-responsive sigma factor σB, control the expression of virulence genes and facilitate invasion of host cells. Listeriosis poses a significant threat to cattle, sheep and goat herds, leading to abortions, septicemia and meningoencephalitis, and ruminants are important reservoirs for Listeria, facilitating transmission to humans. Other Listeria species such as Listeria ivanovii and Listeria innocua can also cause disease in ruminants. Resilience of LM in food processing environments makes it an important foodborne pathogen that is frequently transmitted through contaminated meat and dairy products, with contamination often occurring along the food production chain. In humans, listeriosis primarily affects immunocompromised individuals, pregnant women and the elderly and leads to severe conditions, such as meningitis, septicemia and spontaneous abortion. Possible treatment requires antibiotics that penetrate the blood–brain barrier. Despite the relatively low antimicrobial resistance, multidrug-resistant LM strains have been detected in animals, food and the environment. Controlling and monitoring the disease at the herd level, along with adopting a One Health approach, are crucial to protect human and animal health and to minimize the potential negative impacts on the environment. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes (Lm) is responsible for listeriosis, a serious foodborne disease, with high hospitalization and mortality rates worldwide. The main cause of listeriosis in humans is the consumption of ready-to-eat (RTE) foods; Commission Regulation (EC) No 2073/2005 establishes microbiological criteria for Lm in RTE foods. Raw fish products are widely consumed, e.g., in sushi and various seafood recipes (e.g., carpaccio, sashimi, maki, nigiri, tartare, etc.), but are not subjected to RTE food safety criteria. The aim of our study was to assess the growth potential of Lm in raw sea bass fillets obtained from a leading aquaculture company in Greece. In order to assess the growth of Lm in raw sea bass fillets, we applied the "challenge test", a scientific experiment designed to assess the growth of Lm within a specific food product under controlled conditions. According to our results, and taking into consideration the health risk for the listeriosis-vulnerable population, raw fish products utilized in the preparation of RTE foods, including sushi and an array of seafood dishes, should be incorporated in the Category of Safety Criteria of Regulation (EC) No 2073/2005 "Ready-to-eat food able to support the growth of Listeria monocytogenes". [ABSTRACT FROM AUTHOR]

One of the main objectives of developing new anti-cancer vaccine strategies is to effectively induce CD8+ T cell-mediated anti-tumor immunity. Live recombinant vectors, notably Listeria monocytogenes, have been shown to elicit a robust in vivo CD8+ T-cell response in preclinical settings. Significantly, it has been demonstrated that Listeria induces inflammatory/immunogenic cell death mechanisms such as pyroptosis and necroptosis in immune cells that favorably control immunological responses. Therefore, we postulated that the host's response to Listeria-based vectors and the subsequent induction of CD8+ T cell-mediated immunity would be compromised by the lack of regulatory or effector molecules involved in pyroptosis or necroptosis. To test our hypothesis, we used recombinant L. monocytogenes carrying the ovalbumin gene (LM.OVA) to vaccinate wild-type (WT), caspase-1/11−/−, gsdmd−/−, ripk3−/−, and mlkl−/− C57Bl/6 mice. We performed an in vivo cytotoxicity assay to assess the efficacy of OVA-specific CD8+ T lymphocytes in eliminating target cells in wild-type and genetically deficient backgrounds. Furthermore, we evaluated the specific anti-tumor immune response in mice inoculated with the B16F0 and B16F0.OVA melanoma cell lines. Our findings demonstrated that while caspase-1/11 and GSDMD deficiencies interfere with the rapid control of LM.OVA infection, neither of the KOs seems to contribute to the early activation of OVA-specific CTL responses. In contrast, the individual deficiency of each one of these proteins positively impacts the generation of long-lasting effector CD8+ T cells. [ABSTRACT FROM AUTHOR]

Adding essential oils in an edible coating could be an alternative for the food industry to control foodborne pathogens. In 2014, EFSA published a report highlighting the risk associated with Salmonella spp. and Norovirus in fresh and frozen berries. This study aimed to evaluate the efficacy of an edible coating (RP-7) with carvacrol and citral on reducing the population of Salmonella enterica, Escherichia coli O157:H7, Listeria monocytogenes, and murine Norovirus (MNV-1) in frozen strawberries and blueberries. Before evaluating the efficacy, the best method for applying the coating on fruit was studied. The immersion method was selected, with an optimal drying time of 45 min. After this, the berries were frozen and stored for one, two, three, four, and eight weeks at −18 °C. In strawberries, all bacteria were reduced to below 0.7 log cfu/strawberry in the eighth week, and the MNV-1 infectivity showed a reduction of nearly 2 logarithmic units. In blueberries, S. enterica and E. coli O157:H7 were reduced to 0.8 log cfu/blueberries within a week, and MNV-1 achieved a reduction of 0.8 logarithmic units at the end of the assay. The application of RP-7 affected the studied microorganisms in frozen strawberries and blueberries. [ABSTRACT FROM AUTHOR]

The consumption of raw or smoked fish entails significant microbiological risks, including contamination by pathogens such as Listeria monocytogenes, which can cause severe foodborne illnesses. This study explores the preservative use of piscicolin CM22, a novel bacteriocin derived from the psychrotolerant strain Carnobacterium maltaromaticum CM22, in two types of edible coatings (EC): chitosan-based and fish gelatin-based. An initial in vitro characterization of the technological and antimicrobial properties of these ECs with and without bacteriocin was conducted. The efficacy of the edible coatings was subsequently evaluated through shelf life and challenge tests against L. monocytogenes in raw and smoked fish products. The results demonstrated significant antimicrobial activity, with the chitosan-based coating containing piscicolin CM22 being the most effective in reducing microbial counts and maintaining pH and color stability. Furthermore, in the challenge test studies, both ECs effectively controlled L. monocytogenes, showing significant reductions in bacterial counts compared to the controls in fresh tuna, salmon, and smoked salmon. The ECs containing piscicolin CM22 reduced Listeria counts by up to 4 log CFU/g in raw and smoked fish samples, with effective control in smoked salmon for up to 15 days at refrigeration temperature. While further research is required to fully assess their preservation potential, these findings strongly indicate that piscicolin CM22-functionalized edible coatings hold significant potential for improving the quality and safety of fish products. [ABSTRACT FROM AUTHOR]

Fermented nut-based products, obtained after soaking and fermentation, are gaining increasing interest as animal food substitutes because of ethical, environmental and health reasons. In these products, Lactic Acid Bacteria (LAB) perform the fermentation, leading to matrix acidification and contributing to controlling spoilage and pathogenic microbiota. In this work, LAB strains isolated from an artisanal product and combined with a commercial strain were added as starter cultures during nut soaking to produce a cheese-like fermented plant-based product. Three different LAB consortia were used in challenge tests at laboratory scale against Listeria monocytogenes, Escherichia coli or Salmonella Enteritidis, inoculated in nuts at 5 log CFU/g, and monitored for pathogen survival and matrix acidification. The combination of Lactiplantibacillus plantarum 82 and Leuc. carnosum 4010 resulted in faster acidification (pH value < 4.4 after 18 h instead of 48 h) and the reduction of target pathogens; L. monocytogenes was already absent after seven days from production, and the counts of E. coli or S. Enteritidis were lower with respect to other samples. Thus, this microbial consortium was used for a pilot-scale production in which, beyond safety, the fermented plant-based product was also characterized for aroma profile and phenolic compounds, parameters that are known to be affected by LAB fermentation. The results showed an enhancement of the aroma profile, with an accumulation of molecules able to confer cheese-like notes (i.e., acetoin and diacetyl) and higher phenolic content, as well as the presence of compounds (i.e., phenyllactic acid and hydroxyphenyllactic acid) that could exert antimicrobial activity. This study allowed us to set up a guided fermentation for a cheese-like vegan product, guaranteeing safety and improving aromatic and functional features. [ABSTRACT FROM AUTHOR]

Essential oils (EOs) have antimicrobial properties, but their low solubility in water and strong flavor pose challenges for direct incorporation into food, as they can negatively impact organoleptic properties. To overcome these issues, strategies such as oil-in-water (O/W) nanoemulsions have been developed to improve EO dispersion and protection while enhancing antimicrobial efficacy. The objective of this study was to create sodium alginate-pink pepper essential oil (PPEO) nanoemulsions using microfluidization. Various formulations were assessed for physicochemical, physical, and antimicrobial properties to evaluate their potential in food applications. The microfluidized emulsions and nanoemulsions had droplet sizes ranging from 160 to 443 nm, polydispersity index (PdI) ranging from 0.273 to 0.638, and zeta potential (ζ) ranging from −45.2 to 66.3 mV. The nanoemulsions exhibited Newtonian behavior and remarkable stability after 20 days of storage. Antimicrobial testing revealed effectiveness against Staphylococcus aureus and Listeria monocytogenes, with minimum inhibitory concentrations (MIC) of 200 µg/mL for both microorganisms and minimum bactericidal concentrations (MBC) of 800 µg/mL and 400 µg/mL, respectively, proving that encapsulation of PPEO in nanoemulsions significantly increased its antibacterial activity. These results present the possibility of using PPEO nanoemulsions as a more effective natural alternative to synthetic preservatives in food systems. [ABSTRACT FROM AUTHOR]

Salmonella typhimurium and Listeria monocytogenes are relevant foodborne bacterial pathogens which may cause serious intoxications and infectious diseases in humans. In this study, a sensitive immunochromatographic analysis (ICA) for the simultaneous detection of these two pathogens was developed. For this, test strips containing two test zones with specific monoclonal antibodies (MAb) against lipopolysaccharides of S. typhimurium and L. monocytogenes and one control zone with secondary antibodies were designed, and the double-assay conditions were optimized to ensure high analytical parameters. Prussian blue nanoparticles (PBNPs) were used as nanozyme labels and were conjugated with specific MAbs to perform a sandwich format of the ICA. Peroxidase-mimic properties of PBNPs allowed for the catalytic amplification of the colorimetric signal on test strips, enhancing the assay sensitivity. The limits of detection (LODs) of Salmonella and Listeria cells were 2 × 102 and 7 × 103 cells/mL, respectively. LODs were 100-fold less than those achieved due to the ICA based on the traditional gold label. The developed double ICA was approbated for the detection of bacteria in cow milk samples, which were processed by simple dilution by buffer before the assay. For S. typhimurium and L. monocytogenes, the recoveries from milk were 86.3 ± 9.8 and 118.2 ± 10.5% and correlated well with those estimated by the enzyme-linked immunosorbent assay as a reference method. The proposed approach was characterized by high specificity: no cross-reactivity with other bacteria strains was observed. The assay satisfies the requirements for rapid tests: a full cycle from sample acquisition to result assessment in less than half an hour. The developed ICA has a high application potential for the multiplex detection of other foodborne pathogens. [ABSTRACT FROM AUTHOR]

Food contamination has emerged as a significant global health concern, posing substantial challenges to the food industry. Bacteria are the primary cause of foodborne diseases. Consequently, it is crucial to develop accurate and efficient sensing platforms to detect foodborne bacteria in food products. Among various detection methods, biosensors have emerged as a promising solution due to their portability, affordability, simplicity, selectivity, sensitivity, and rapidity. Electrospun nanofibers have gained increasing popularity in enhancing biosensor performance. These nanofibers possess a distinctive three-dimensional structure, providing a large surface area and ease of preparation. This review provides an overview of the electrospinning technique, nanofibers and nanofiber-based biosensors. It also explores their mechanisms and applications in the detection of foodborne bacteria such as Salmonella, Listeria monocytogenes (L. monocytogenes), Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Pseudomonas putida (P. putida). [ABSTRACT FROM AUTHOR]

Ozone is a molecule that has gained increasing interest in recent years by food industries for sanitization of food-grade surfaces. Compared to chemical sanitizers such as chlorine, hydrogen peroxide, or peracetic acid, ozone shows undeniable advantages, such as the absence of by-products that should affect human health or the possibility of generating it when needed. Therefore, the aim of this paper was the assessment of the resistance to ozonized water of two pathogenic bacteria (Listeria monocytogenes, Salmonella) and of three airborne food-spoiling fungi (Aspergillus brasiliensis, Hyphopichia burtonii, and Penicillium nordicum) inoculated on stainless steel tiles and treated in static conditions with 1 to 6 mg L−1 (pathogens) or 8.5 mg L−1 (filamentous fungi). Ozonized water gave different results based on the tested microorganisms: pathogenic bacteria proved markedly more sensible to ozone than filamentous fungi, even if great differences were observed at inter- and intra-specific levels for both categories of microorganisms. Nevertheless, the non-linear inactivation kinetics of the studied strains made the calculation of a punctual F-value difficult, so in industrial practice, adequate tailoring of the treatments to be applied, based on the registered extrinsic factors and the industrial bio-burden, would be appropriate. [ABSTRACT FROM AUTHOR]

Given the persistent occurrence of foodborne illnesses linked to both raw and processed vegetables, understanding microbial behavior in these foods under distribution conditions is crucial. This study aimed to develop predictive growth models for Salmonella spp. and Listeria monocytogenes in raw (mung bean sprouts, onion, and cabbage) and processed vegetables (shredded cabbage salad, cabbage and onion juices) at various temperatures, ranging from 4 to 36 °C. Growth models were constructed and validated using isolated strains of Salmonella spp. (S. Bareilly, S. Enteritidis, S. Typhimurium) and L. monocytogenes (serotypes 1/2a and 1/2b) from diverse food sources. The minimum growth temperatures for Salmonella varied among different vegetable matrices: 8 °C for mung bean sprouts, 9 °C for both onion and cabbage, and 10 °C for ready-to-eat (RTE) shredded cabbage salad. Both pathogens grew in cabbage juice at temperatures above 17 °C, while neither demonstrated growth in onion juice, even at 36 °C. Notably, Salmonella spp. exhibited faster growth than L. monocytogenes in all tested samples. At 8 °C, the lag time (LT) and specific growth rate (SGR) for Salmonella spp. in mung bean sprouts were approximately tenfold longer and threefold slower, respectively, compared to those at 10 °C. A decrease in refrigerator storage temperature by 1 or 2 degrees significantly prevented the growth of Salmonella in raw vegetables. These findings offer valuable insights into assessing the risk of foodborne illness associated with the consumption of raw and processed vegetables and inform management strategies in mitigating these risks. [ABSTRACT FROM AUTHOR]

L. monocytogenes is considered one of the most dangerous foodborne pathogens. This study aimed to determine the occurrence of L. monocytogenes in RTE meat products from southern Poland, including serogroups and antimicrobial susceptibility, and to assess the usefulness of MALDI-TOF MS as a tool for identifying L. monocytogenes. A total of 848 production batches of RTE meat products were analyzed for L. monocytogenes. All L. monocytogenes isolates were serotyped using the multiplex PCR method, tested for antimicrobial susceptibility using the disk diffusion method and identified using the MALDI-TOF MS method. L. monocytogenes was detected in 52/848 batches of RTE meat products (6.13%). The isolates belonged to four serogroups: 17/52 (33%) isolates to IVb; 15/52 (29%) isolates to IIa; 10/52 (19%) isolates to IIc and 10/52 (19%) isolates to IIb. All isolates (52/52) showed susceptibility to the tested antimicrobials. Using MALDI-TOF MS, 10/52 isolates (19.2%) were identified at the level of secure genus identification, probable species identification; 37/52 isolates (71.2%) were identified at the level of probable genus identification; 3/52 isolates (5.8%) were incorrectly identified as L. innocua; and 2/52 isolates (3.8%) were not identified. The occurrence of L. monocytogenes in RTE meat products was low. Almost half of the analyzed isolates were L. monocytogenes of serogroups, which are most often associated with listeriosis in humans in Poland. All isolates showed susceptibility to five commonly used antimicrobials for treating listeriosis. The use of MALDI-TOF MS as a tool for the identification of L. monocytogenes indicated its limitations related to the insufficient representation of the pathogen in the reference database. [ABSTRACT FROM AUTHOR]

Listeria are Gram-negative intracellular foodborne pathogens that can cause invasive infections with high mortality rates. In this work, the antibacterial activity of ten essential oils, infusion extracts, and decoction extracts of some medicinal plants was tested against Listeria monocytogenes and listeria ivanovii strains. The effects of different physical conditions including temperature, pH, sodium chloride, and some organic acids were studied. The results showed that the water extracts gave the maximum bacterial inhibition, while ethanolic extract was inactive against the tested Listeria spp. The antibiotic sensitivity of L. monocytogenes LMG10470 and L. ivanovii LMZ11352 was tested against five antibiotics including imipenem, levofloxacin, amikacin, ampicillin, and amoxicillin. Imipenem was the most effective antibiotic, resulting in inhibition zones of 40 mm and 31 mm for L. monocytogenes and L. ivanovii, respectively. When imipenem mixed with Syzygium aromaticum oil, Salvia officinalis oil, Pimpinella anisum infusion, and Mentha piperita infusion each, the water extract of Moringa oleifera leaves and seeds against LMG10470 and LMZ11352 resulted in broader antibacterial activity. The antimicrobial activity of both Pimpinella anisum and Mentha piperita plant extracts is related to a variety of bioactive compounds indicated by gas chromatography–mass spectrometry analysis of these two plant extracts. These two plant extracts seemed to contain many chemical compounds elucidated by gas chromatography–mass spectrometry (GC-MS) and infrared radiation spectra. These compounds could be classified into different chemical groups such as ethers, heterocyclic compounds, aromatic aldehydes, condensed heterocyclic compounds, ketones, alicyclic compounds, aromatics, esters, herbicides, saturated fatty acids, and unsaturated fatty acids. The use of these natural compounds seems to be a useful technological adjuvant for the control of Listeria spp. in foods. [ABSTRACT FROM AUTHOR]

The present study describes the genetic characterization of L. monocytogenes strains found in the Republic of Kosovo's food chain. From 2016 to 2022, 995 samples were collected. Overall, 648 samples were from ready-to-eat (RTE) food products, 281 from food products consumed cooked (FPCC), 60 from raw materials, and 6 from environmental samples. Overall, 11.76% (117 out of 995) of the samples were contaminated by L. monocytogenes, comprising 6.33% (41 out of 648) from RTE products, 14.95% (42 out of 281) from FPCC, 55.00% (33 out of 60) from raw materials, and 16.66% (1 out of 6) from environmental samples. All isolates were subjected to molecular serotyping and clonal complex (CC) identification by using real-time PCR, as well as multilocus sequence typing. All isolates were grouped into four molecular serotypes, IIa (34.19%), IIb (3.48%), IIc (32.48%), and IVb (29.91%), as well as Lineage I (33.33%) and Lineage II (66.66%). In total, 14 CCs were identified from 41 RTE isolates; however, CC29 (7), CC2 (6), and CC6 (6) were the most dominant. By contrast, CC9 was by far the most represented CC in both FPCC (21) and RM (14). Moreover, 30 isolates expressed CC1, CC2, CC4, or CC6, which are particularly associated with severe human infections. [ABSTRACT FROM AUTHOR]

Polar habitats offer excellent sites to isolate unique bacterial strains due to their diverse physical, geochemical, and biological factors. We hypothesize that the unique environmental conditions of polar regions select for distinct strains of lactic acid bacteria (LAB) with novel biochemical properties. In this study, we characterized ten strains of psychrotrophic LAB isolated from hitherto poorly described sources—High Arctic and maritime Antarctic soils and soil-like materials, including ornithogenic soils, cryoconites, elephant seal colonies, and postglacial moraines. We evaluated the physiological and biochemical properties of the isolates. Based on 16S rRNA and housekeeping genes, the four LAB strains were assigned to three Carnobacterium species: C. alterfunditum, C. maltaromaticum, and C. jeotgali. The remaining strains may represent three new species of the Carnobacterium genus. All isolates were neutrophilic and halophilic psychrotrophs capable of fermenting various carbohydrates, organic acids, and alcohols. The identified metabolic properties of the isolated Carnobacterium strains suggest possible syntrophic interactions with other microorganisms in polar habitats. Some showed antimicrobial activity against food pathogens such as Listeria monocytogenes and human pathogens like Staphylococcus spp. Several isolates exhibited unique metabolic traits with potential biotechnological applications that could be more effectively exploited under less stringent technological conditions compared to thermophilic LAB strains, such as lower temperatures and reduced nutrient concentrations. Analysis of extrachromosomal genetic elements revealed 13 plasmids ranging from 4.5 to 79.5 kb in five isolates, featuring unique genetic structures and high levels of previously uncharacterized genes. This work is the first comprehensive study of the biochemical properties of both known and new Carnobacterium species and enhances our understanding of bacterial communities in harsh and highly selective polar soil ecosystems. [ABSTRACT FROM AUTHOR]

Listeria pathogenicity island 1 (LIPI-1) is a genetic region containing a cluster of genes essential for virulence of the bacterial pathogen Listeria monocytogenes. Main virulence factors in LIPI-1 include long 5′ untranslated regions (5′UTRs), among which is Rli51, a small RNA (sRNA) in the 5′UTR of the Zn-metalloprotease-coding mpl. So far, Rli51 function and molecular mechanisms have remained obscure. Here, we show that Rli51 exhibits a dual mechanism of regulation, functioning as a cis- and as a trans-acting sRNA. Under nutrient-rich conditions, rli51-mpl transcription is prematurely terminated, releasing a short 121-nucleotide-long sRNA. Rli51 is predicted to function as a transcription attenuator that can fold into either a terminator or a thermodynamically more stable antiterminator. We show that the sRNA Rli21/RliI binds to a single-stranded RNA loop in Rli51, which is essential to mediate premature transcription termination, suggesting that sRNA binding could stabilize the terminator fold. During intracellular infection, rli51 transcription is increased, which generates a higher abundance of the short Rli51 sRNA and allows for transcriptional read-through into mpl. Comparative intracellular bacterial transcriptomics in rli51-null mutants and the wild-type reference strain EGD-e suggests that Rli51 upregulates iron-scavenging proteins and downregulates virulence factors from LIPI-1. MS2 affinity purification confirmed that Rli51 binds transcripts of the heme-binding protein Lmo2186 and Lmo0937 in vivo. These results prove that Rli51 functions as a trans-acting sRNA in intracellular bacteria. Our research shows a growth condition-dependent mechanism of regulation for Rli51, preventing unintended mpl transcription in extracellular bacteria and regulating genes important for virulence in intracellular bacteria. [ABSTRACT FROM AUTHOR]

Using sous-vide technology in combination with essential oils offers the potential to extend the preservation of food items while preserving their original quality. This method aligns with the growing consumer demand for safer and healthier food production practices. This study aimed to assess the suitability of minimal processing of game meat and the effectiveness of vacuum packaging in combination with Piper nigrum essential oil (PNEO) treatment to preserve red deer meat samples inoculated with Listeria monocytogenes. Microbial analyses, including total viable count (TVC) for 48 h at 30 °C, coliform bacteria (CB) for 24 h at 37 °C, and L. monocytogenes count for 24 h at 37 °C, were conducted. The cooking temperature of the sous-vide was from 50 to 65 °C and the cooking time from 5 to 20 min. Additionally, the study monitored the representation of microorganism species identified through mass spectrometry. The microbiological quality of red deer meat processed using the sous-vide method was monitored over 14 days of storage at 4 °C. The results indicated that the TVC, CB, and L. monocytogenes counts decreased with the temperature and processing time of the sous-vide method. The lowest counts of individual microorganism groups were observed in samples treated with 1% PNEO. The analysis revealed that PNEO, in combination with the sous-vide method, effectively reduced L. monocytogenes counts and extended the shelf life of red deer meat. Kocuria salsicia, Pseudomonas taetrolens, and Pseudomonas fragi were the most frequently isolated microorganism species during the 14-day period of red deer meat storage prepared using the sous-vide method. [ABSTRACT FROM AUTHOR]

Our work investigated the antimicrobial and prebiotic properties of basil, mint, oregano, rosemary, savory, and thyme honey. The potential antimicrobial action, assessed against the pathogens Acinetobacter baumannii, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus, evidenced the capacity of the honey to influence the pathogenic hydrophobicity and hemolytic activities. Honey inhibited pathogen biofilms, acting especially on the mature biofilms, with inhibition rates of up to 81.62% (caused by the presence of mint honey on L. monocytogenes). S. aureus biofilms were the most susceptible to the presence of honey, with inhibition rates up of to 67.38% in the immature form (caused by basil honey) and up to 80.32% in the mature form (caused by mint honey). In some cases, the amount of nuclear and proteic material, evaluated by spectrophotometric readings, if also related to the honey's biofilm inhibitory activity, let us hypothesize a defective capacity of building the biofilm scaffold or bacterial membrane damage or an incapability of producing them for the biofilm scaffold. The prebiotic potentiality of the honey was assessed on Lacticaseibacillus casei Shirota, Lactobacillus gasseri, Lacticaseibacillus paracasei subsp. paracasei, and Lacticaseibacillus rhamnosus and indicated their capacity to affect the whole probiotic growth and in vitro adhesive capacity, as well as the antioxidant and cytotoxic abilities, and to inhibit, mainly in the test performed with the L. casei Shirota, L. gasseri, and L. paracasei supernatants, the immature biofilm of the pathogens mentioned above. [ABSTRACT FROM AUTHOR]

This research aimed to identify the probiotic features of Yarrowia lipolytica strains isolated from olive oils in Turkey. The in vitro survival capabilities of Y. lipolytica strains in gastric and pancreatic solutions were assessed. The hydrophobicity of Y. lipolytica strains was determined to be between 25.8% and 46.08% for xylene, 22.5% and 45.85% for chloroform, and 14.83% and 37.09% for ethyl acetate. In addition, auto-aggregation values were measured as 11.07–60.35%; 16.28–67.70% and 42.89–85.21% after 2, 4 and 24 h of incubation, respectively. The Y. lipolytica strains tested in this study demonstrated aggregation ability against the pathogens Escherichia coli ATCC 25922, Salmonella typhimurium ATCC 14028, Staphylococcus aureus ATCC 25923 and Listeria monocytogenes ATCC 7644. Antibiotic resistance and hemolytic activities were also checked to ensure the safety of the Y. lipolytica. Cholesterol removal by Y. lipolytica strains ranged from 12.30% to 47.42%, and their free radical scavenging activity varied between 2.85% and 39.10%. Out of 13 Y. lipolytica samples from 10 different olive oil sources, Y. lipolytica Y6, Y7, and Y11 exhibited the best strains with probiotic potential properties. This study discovered that Y. lipolytica with probiotic properties can be isolated in olive oil samples, a finding that has not been previously documented in the literature and may have potential industrial applications [ABSTRACT FROM AUTHOR]

Listeria monocytognes is an emerging pathogen responsible for the serious foodborne disease, listeriosis. The commensal gut microbiota is the first line of defense against pathogen internalization. The gut microbiome can be modified by prebiotic substrates, which are frequently added to food products and dietary supplements. Prebiotics should selectively support the growth of beneficial microbes and thus improve host health. Nevertheless, little is known about their effect on the growth of L. monocytogenes. The aim of this study was to evaluate the growth ability of four L. monocytogenes strains, representing the most common serotypes, on prebiotic oligosaccharides (beta-(1,3)-D-glucan, inulin, fructooligosaccharides, galactooligosaccharides, lactulose, raffinose, stachyose and 2′-fucosyllactose and a mixture of human milk oligosaccharides) as a sole carbon source. The results showed that only beta-(1,3)-D-glucan was metabolized by L. monocytogenes. These cell culture data suggest that beta-(1,3)-D-glucan may not be selectively utilized by healthy commensal bacteria, and its role in intestinal pathogen growth warrants further exploration in vivo. [ABSTRACT FROM AUTHOR]

Lately, the inclusion of additional lactic acid bacteria (LAB) strains to cheeses is becoming more popular since they can affect cheese's nutritional, technological, and sensory properties, as well as increase the product's safety. This work studied the effect of Lactiplantibacillus pentosus L33 and Lactiplantibacillus plantarum L125 free cells and supernatants on feta cheese quality and Listeria monocytogenes fate. In addition, rapid and non-invasive techniques such as Fourier transform infrared (FTIR) and multispectral imaging (MSI) analysis were used to classify the cheese samples based on their sensory attributes. Slices of feta cheese were contaminated with 3 log CFU/g of L. monocytogenes, and then the cheese slices were sprayed with (i) free cells of the two strains of the lactic acid bacteria (LAB) in co-culture (F, ~5 log CFU/g), (ii) supernatant of the LAB co-culture (S) and control (C, UHT milk) or wrapped with Na-alginate edible films containing the pellet (cells, FF) or the supernatant (SF) of the LAB strains. Subsequently, samples were stored in air, in brine, or in vacuum at 4 and 10 °C. During storage, microbiological counts, pH, and water activity (aw) were monitored while sensory assessment was conducted. Also, in every sampling point, spectral data were acquired by means of FTIR and MSI techniques. Results showed that the initial microbial population of Feta was ca. 7.6 log CFU/g and consisted of LAB (>7 log CFU/g) and yeast molds in lower levels, while no Enterobacteriaceae were detected. During aerobic, brine, and vacuum storage for both temperatures, pathogen population was slightly postponed for S and F samples and reached lower levels compared to the C ones. The yeast mold population was slightly delayed in brine and vacuum packaging. For aerobic storage at 4 °C, an elongation in the shelf life of F samples by 4 days was observed compared to C and S samples. At 10 °C, the shelf life of both F and S samples was extended by 13 days compared to C samples. FTIR and MSI analyses provided reliable estimations of feta quality using the PLS-DA method, with total accuracy (%) ranging from 65.26 to 84.31 and 60.43 to 89.12, respectively. In conclusion, the application of bioprotective LAB strains can result in the extension of feta's shelf life and provide a mild antimicrobial action against L. monocytogenes and spoilage microbiota. Furthermore, the findings of this study validate the effectiveness of FTIR and MSI techniques, in tandem with data analytics, for the rapid assessment of the quality of feta samples. [ABSTRACT FROM AUTHOR]

The aim of this work was to assess the microbiological safety and quality of horsemeat. A total of 19 fresh horsemeat samples were analysed. Mesophile counts were 4.89 ± 1.08 log CFU/g, and Enterobacteriaceae, Staphylococcus spp., and enterococci were only isolated from 36.84%, 21.05%, and 15.79% of the samples, respectively. Neither Staphylococcus aureus nor Escherichia coli were found in any sample. Listeria spp. and Listeria monocytogenes were detected in 31.58% and 21.05% of the samples, respectively. Campylobacter jejuni was not detected in any sample. The dominant bacteria were lactic acid bacteria. Seven different Staphylococcus spp. were identified, the most common being S. delphini, S. saprophyticus, and S. warneri. S. delphini showed resistance against mupirocin and cefoxitin. All the L. monocytogenes strains showed resistance against ampicillin, cefotaxime, and oxacillin. Multi-resistant Yersinia enterocolitica, Stenotrophomonas maltophilia, and Vagococcus. fluvialis strains were found, with resistance to 11, 7, and 8 antibiotics, respectively, causing significant concern. Therefore, specific actions should be taken to decrease the contamination of horsemeat. [ABSTRACT FROM AUTHOR]