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Importance: In developed countries, the human diet is predominated by food commodities, which have been manufactured, processed, and stored in a food production facility. Little is known about the application of metagenomic sequencing approaches for detecting foodborne pathogens, such as L. monocytogenes , and characterizing microbial diversity in food production ecosystems. In this work, we investigated the utility of 16S rRNA amplicon and quasimetagenomic sequencing for the taxonomic and phylogenetic classification of Listeria culture enrichments of environmental swabs collected from dairy and seafood production facilities. We demonstrated that single-nucleotide polymorphism (SNP) analyses of L. monocytogenes metagenome-assembled genomes (MAGs) from quasimetagenomic data sets can achieve similar resolution as culture isolate whole-genome sequencing. To further understand the impact of genome coverage on MAG SNP cluster resolution, an in silico downsampling approach was employed to reduce the percentage of target pathogen sequence reads, providing an initial estimate of required MAG coverage for subtyping resolution of L. monocytogenes ., Competing Interests: The authors declare no conflict of interest.

Food-borne pathogenic bacteria are a major public health concern globally. Traditional control methods using antibiotics have limitations, leading to the exploration of alternative strategies. Essential oils such as cardamom possess antimicrobial properties and have shown efficacy against food-borne pathogenic bacteria. The utilization of essential oils and their bioactive constituents in food preservation is a viable strategy to prolong the shelf-life of food products while ensuring their quality and safety. To the best of our knowledge, there are no studies that have utilized 1,8-cineole (the main active constituent of cardamom essential oil) as a preservative in meat, so this study might be the first to utilize 1,8-cineole as an antibacterial agent in meat preservation. The application of 1,8-cineole had a significant suppressive impact on the growth rate of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium in meat samples stored for 7 days at 4 °C. Additionally, the surface color of the meat samples was not negatively impacted by the application of 1,8-cineole. The minimum inhibitory concentration was 12.5-25 mg/ml, and the minimum bactericidal concentration was 25-50.0 mg/ml. The bacterial cell membrane may be the target of cardamom, causing leakage of intracellular proteins, ATP, and DNA. The obtained data in this study may pave a new avenue for using 1,8-cineole as a new perspective for dealing with this problem of food-borne pathogens and food preservation, such as meat., Competing Interests: Declaration of competing Interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Measuring microbial inactivation in food is useful for food technology as it allows for predicting the growth or death of microorganisms. This study aimed to investigate the effect of gamma irradiation on the lethality of microorganisms inoculated in milk, estimate the mathematical model of inactivation of each microorganism, and evaluate kinetic indices to determine the efficient dose in the treatment of milk. Raw milk samples were inoculated with cultures of Salmonella enterica subsp. enterica serovar Enteritidis (ATCC 13076), Escherichia coli (ATCC 8739), and Listeria innocua (ATCC 3309), irradiated at doses of 0, 0.5, 1, 1.5, 2, 2.5, and 3 kGy. The fitting of the models to the microbial inactivation data was performed using the GinaFIT software. The results demonstrated a significant effect of irradiation doses on the population of microorganisms, with the application of a dose of 3 kGy, a reduction of approximately 6 logarithmic cycles is observed for L. innocua and 5 for S. Enteritidis and E. coli. The model with the best fit was different for each microorganism studied: for L. innocua, the model was log-linear + shoulder; for S. Enteritidis and E. coli, the model that showed the best fit was the biphasic. The studied model fitted well (R 2 ≥ 0.9; R 2 adj. ≥ 0.9 and smallest RMSE values) for the inactivation kinetics. The lethality of the treatment, considering a reduction in the 4D value, was achieved with the predicted dose of doses of ±2.22, ±2.10, and ±1.77 kGy, for L. innocua, S. Enteritidis, and E. coli, respectively., (© 2023. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

We evaluated the combined effects of vacuumed hydrogen peroxide vapour (VHPV) and vacuum-sealed dry heat (vacuum heat, VH) to inactivate food-borne pathogens (Salmonella Typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes) on alfalfa seeds. Alfalfa seeds inoculated with food-borne pathogens were sequentially treated initially with 1·0 ml of 0 or 30% VHPV for 1 min and later with dry heat (DH) or VH for 2 h, and the rate of seed germination was evaluated. The combination treatment decreased the populations of three food-borne pathogens below the limit of detection (1·0 log CFU per gram) on alfalfa seeds without decreasing germinability. The sequential treatment using VHPV and VH greatly reduced the total treatment time needed to inactivate pathogens on alfalfa seeds by more than 5 log CFU per gram. These results demonstrate that a combination of VHPV and VH has potentially employed as a new method for pasteurization of alfalfa seeds without affecting their germinability., (© 2022 The Society for Applied Microbiology.)

In spite of its relevance as a foodborne pathogen, we have limited knowledge about Listeria monocytogenes in the environment. L. monocytogenes outbreaks have been linked to fruits and vegetables; thus, a better understanding of the factors influencing its ability to colonize plants is important. We tested how environmental factors and other soil- and plant-associated bacteria influenced L. monocytogenes' ability to colonize plant roots using Arabidopsis thaliana seedlings in a hydroponic growth system. We determined that the successful root colonization of L. monocytogenes 10403S was modestly but significantly enhanced by the bacterium being pregrown at higher temperatures, and this effect was independent of the biofilm and virulence regulator PrfA. We tested 14 rhizosphere-derived bacteria for their impact on L. monocytogenes 10403S, identifying one that enhanced and 10 that inhibited the association of 10403S with plant roots. We also characterized the outcomes of these interactions under both coinoculation and invasion conditions. We characterized the physical requirements of five of these rhizobacteria to impact the association of L. monocytogenes 10403S with roots, visualizing one of these interactions by microscopy. Furthermore, we determined that two rhizobacteria (one an inhibitor, the other an enhancer of 10403S root association) were able to similarly impact 10 different L. monocytogenes strains, indicating that the effects of these rhizobacteria on L. monocytogenes are not strain specific. Taken together, our results advance our understanding of the parameters that affect L. monocytogenes plant root colonization, knowledge that may enable us to deter its association with and, thus, downstream contamination of, food crops. IMPORTANCE Listeria monocytogenes is ubiquitous in the environment, being found in or on soil, water, plants, and wildlife. However, little is known about the requirements for L. monocytogenes' existence in these settings. Recent L. monocytogenes outbreaks have been associated with contaminated produce; thus, we used a plant colonization model to investigate factors that alter L. monocytogenes' ability to colonize plant roots. We show that L. monocytogenes colonization of roots was enhanced when grown at higher temperatures prior to inoculation but did not require a known regulator of virulence and biofilm formation. Additionally, we identified several rhizobacteria that altered the ability of 11 different strains of L. monocytogenes to colonize plant roots. Understanding the factors that impact L. monocytogenes physiology and growth will be crucial for finding mechanisms (whether chemical or microbial) that enable its removal from plant surfaces to reduce L. monocytogenes contamination of produce and eliminate foodborne illness.

Smoked salmon is a highly appreciated delicatessen product. Nevertheless, this ready-to-eat (RTE) product is considered at risk for Listeria monocytogenes, due to both the prevalence and growth potential of this bacteria on the product. Biopreservation may be considered a mild and natural effective strategy for minimizing this risk. In this study, we evaluated the following three potential bioprotective lactic acid bacterial strains against L. monocytogenes in three smoked salmon types with different physicochemical characteristics, primarily fat, moisture, phenol and acid acetic content: two bacteriocin-like producers that were isolated from smoked salmon and identified as Lactobacillus curvatus and Carnobacterium maltaromaticum and a recognized bioprotective bacteriocin producer from meat origin, Lactobacillus sakei CTC494. L. sakei CTC494 inhibited the growth of L. monocytogenes after 21 days of storage at 8 °C in all the products tested, whereas L. curvatus CTC1742 only limited the growth of the pathogen (<2 log increase). The effectiveness of C. maltaromaticum CTC1741 was dependent on the product type; this strain limited the growth of the pathogen in only one smoked salmon type. These results suggest that the meat-borne starter culture, L. sakei CTC494, may potentially be used as a bioprotective culture to improve the food safety of cold-smoked salmon., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The aim of this study was to determine the effects of marination liquids prepared with koruk juice and dried koruk pomace in terms of meat safety. In the study, marination liquids containing two different concentrations of koruk juice (25% and 50%) or dried koruk pomace (1% and 2%) were prepared separately with or without ingredients (1% salt and 0.1% thyme). Meat samples inoculated with two different levels (≅3 log and ≅6 log) of food-borne pathogens (S. Typhimurium, E. coli O157:H7 and L. monocytogenes) were marinated at 4 °C for different times (2, 24 and 48 h) and the effects of the treatment on target pathogens were determined. As a result of marinating process, the counts of S. Typhimurium, E. coli O157:H7 and L. monocytogenes inoculated at high levels (≅6 log) on meat samples were reduced in the range of 0.109-2.648 log CFU/g, 0.264-3.373 log CFU/g and 0.023-2.781 log CFU/g, respectively. The most effective treatment in reducing the counts of S. Typhimurium and E. coli O157:H7 was achieved by marination with ML1 (50% koruk juice + 50% water) for 48 h, while marination with ML2 (50% koruk juice + 50% water + 1% salt + 0.1% thyme) for 24 h was the most effective treatment for L. monocytogenes. When low inoculum levels were used (≅3 log), the counts of pathogens on meat samples were determined under detection limits after marination even for 2 h application. The results of sensory evaluation showed that the sample marinated with ML2 for 48 h was the most favored sample in terms of appearance, color, texture, taste and overall appreciation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The microbiological safety of fresh produce is monitored almost exclusively by culture-based detection methods. However, bacterial food-borne pathogens are known to enter a viable-but-nonculturable (VBNC) state in response to environmental stresses such as chlorine, which is commonly used for fresh produce decontamination. Here, complete VBNC induction of green fluorescent protein-tagged Listeria monocytogenes and Salmonella enterica serovar Thompson was achieved by exposure to 12 and 3 ppm chlorine, respectively. The pathogens were subjected to chlorine washing following incubation on spinach leaves. Culture data revealed that total viable L. monocytogenes and Salmonella Thompson populations became VBNC by 50 and 100 ppm chlorine, respectively, while enumeration by direct viable counting found that chlorine caused a <1-log reduction in viability. The pathogenicity of chlorine-induced VBNC L. monocytogenes and Salmonella Thompson was assessed by using Caenorhabditis elegans Ingestion of VBNC pathogens by C. elegans resulted in a significant life span reduction ( P = 0.0064 and P < 0.0001), and no significant difference between the life span reductions caused by the VBNC and culturable L. monocytogenes treatments was observed. L. monocytogenes was visualized beyond the nematode intestinal lumen, indicating resuscitation and cell invasion. These data emphasize the risk that VBNC food-borne pathogens could pose to public health should they continue to go undetected. IMPORTANCE Many bacteria are known to enter a viable-but-nonculturable (VBNC) state in response to environmental stresses. VBNC cells cannot be detected by standard laboratory culture techniques, presenting a problem for the food industry, which uses these techniques to detect pathogen contaminants. This study found that chlorine, a sanitizer commonly used for fresh produce, induces a VBNC state in the food-borne pathogens Listeria monocytogenes and Salmonella enterica It was also found that chlorine is ineffective at killing total populations of the pathogens. A life span reduction was observed in Caenorhabditis elegans that ingested these VBNC pathogens, with VBNC L. monocytogenes as infectious as its culturable counterpart. These data show that VBNC food-borne pathogens can both be generated and avoid detection by industrial practices while potentially retaining the ability to cause disease., (Copyright © 2018 Highmore et al.)

ABSTRACT Microorganisms frequently colonize surfaces within food production facilities. Detection of Listeria monocytogenes in this setting relies on culture-dependent methods, but the complex dynamics of bacterial interactions within these environments and their impact on pathogen detection remain largely unexplored. To address this challenge, we applied both 16S rRNA and shotgun quasimetagenomic (enriched microbiome) sequencing of swab culture enrichments from five seafood and seven dairy production environments. Utilizing 16S rRNA amplicon sequencing, we observed variability between 355 samples taken from these 12 production facilities and a distinctive microbiome for each environment. With shotgun quasimetagenomic sequencing, we were able to assemble L. monocytogenes metagenome-assembled genomes (MAGs) from 28 of the 32 culture-positive samples. We compared these MAGs to their corresponding whole-genome sequencing assemblies, which resulted in two polyphyletic clades consisting of L. monocytogenes lineages I and II with 13,195 and 25,556 single-nucleotide polymorphism sites, respectively. The remaining four MAGs did not produce sufficient genome coverage. To understand and establish limits for pathogen detection and subtyping using shotgun quasimetagenomics, these same data sets were downsampled in slilico to produce a titration series of abundances of L. monocytogenes and analyzed. Pathogen detection was achieved for all downsampled data sets, even those with only 3× genome coverage. This study contributes to the understanding of microbial diversity within food production environments and presents insights into the level of genome coverage needed in a metagenome sequencing data set to detect, subtype, and source track a foodborne pathogen IMPORTANCE In developed countries, the human diet is predominated by food commodities, which have been manufactured, processed, and stored in a food production facility. Little is known about the application of metagenomic sequencing approaches for detecting foodborne pathogens, such as L. monocytogenes, and characterizing microbial diversity in food production ecosystems. In this work, we investigated the utility of 16S rRNA amplicon and quasimetagenomic sequencing for the taxonomic and phylogenetic classification of Listeria culture enrichments of environmental swabs collected from dairy and seafood production facilities. We demonstrated that single-nucleotide polymorphism (SNP) analyses of L. monocytogenes metagenome-assembled genomes (MAGs) from quasimetagenomic data sets can achieve similar resolution as culture isolate whole-genome sequencing. To further understand the impact of genome coverage on MAG SNP cluster resolution, an in silico downsampling approach was employed to reduce the percentage of target pathogen sequence reads, providing an initial estimate of required MAG coverage for subtyping resolution of L. monocytogenes.

The problem of microbial biofilms has come to the fore alongside food, pharmaceutical, and healthcare industrialization. The development of new antibiofilm products has become urgent, but it includes bioprospecting and is time and money-consuming. Contemporary efforts are directed at the pursuit of effective compounds of natural origin, also known as "green" agents. Mushrooms appear to be a possible new source of antibiofilm compounds, as has been demonstrated recently. The existing modeling methods are directed toward predicting bacterial biofilm formation, not in the presence of antibiofilm materials. Moreover, the modeling is almost exclusively targeted at biofilms in healthcare, while modeling related to the food industry remains under-researched. The present study applied an Artificial Neural Network (ANN) model to analyze the anti-adhesion and anti-biofilm-forming effects of 40 extracts from 20 mushroom species against two very important food-borne bacterial species for food and food-related industries—Listeria monocytogenes and Salmonella enteritidis. The models developed in this study exhibited high prediction quality, as indicated by high r2 values during the training cycle. The best fit between the modeled and measured values was observed for the inhibition of adhesion. This study provides a valuable contribution to the field, supporting industrial settings during the initial stage of biofilm formation, when these communities are the most vulnerable, and promoting innovative and improved safety management. [ABSTRACT FROM AUTHOR]

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A culture medium contains basic elements (water, nutrients), to which are added various supplements capable of contributing to the growth of the bacteria of interest, and at the same time, inhibiting the association flora. This study aimed for testing and optimization of special supplemented culture media used for diagnosis of microbial origin foodborne pathogens. For this, performance criteria (productivity, selectivity, and specificity) of ten different culture media used for the identification and characterization of most common bacteria (i.e., Listeria monocytogenes, Salmonella spp., Escherichia coli and Staphylococcus aureus) involved in food poisoning, were investigated. For the evaluation of the performance parameters, artificial contamination was performed with Reference Materials (MR) represented by reference strains, on two levels of contamination (low and high) and blank samples. On the qualitative methods (detection of L. monocytogenes and Salmonella spp.), selectivity, specificity, accuracy, concordance and evaluation of the detection limit at 50% (LOD50) were tested; while, on the quantitative methods (enumeration of E. coli and S. aureus), repeatability, reproducibility, critical difference and measurement uncertainty were assessed. For the qualitative methods (detection of L. monocytogenes and Salmonella spp.), the evaluated parameters showed values between 82-100% and 0.429-0.564 cfu/25 g for LOD50, respectively. For the quantitative methods (enumeration of E. coli and S. aureus), the values obtained had a measurement uncertainty between 0.24-0.26 log10 cfu/g). The performance criteria (productivity, selectivity and specificity) of the culture media investigated were successfully achieved. These findings on the benefits of the addition of supplements for the culture media used to diagnose food poisoning provide further evidence of the importance of additional components with the role of enrichment, stimulation, inhibition, selection and highlighting of metabolic and enzymatic equipment. [ABSTRACT FROM AUTHOR]

Bacterial strains with inhibitory effect on Salmonella Hartford, Listeria monocytogenes, Yersinia enterocolitica, and Escherichia coli, respectively, were isolated. Out of the 64 bacteria originated from food processing environments, 20 could inhibit at least one of the tested pathogens, and it was proved that growth decline of the pathogenic bacteria was more remarkable by co-culturing than by using cell-free supernatants of the isolates. Seven different genera (Pseudomonas, Bacillus, Paenibacillus, Macrococcus, Staphylococcus, Serratia, and Rothia) reduced the pathogens' growth during the time period of analysis, and the strongest inhibitory effect was observed after 24 h between 15 and 30 °C. Sensitivity of the tested human pathogenic bacteria against the inhibitory strains was distinct, as Y. enterocolitica could be inhibited by numerous isolates, while S. Hartford proved to be the most resistant. Our results reveal that the isolated bacteria or their excreted metabolites could hinder pathogen growth when used in sufficient quantities. [ABSTRACT FROM AUTHOR]

The aim of this work was to examine the effect of modified atmosphere packaging on the physicochemical and microbiological changes of Graviera Agraphon cheese during refrigerated storage. Blocks of Graviera Agraphon cheese weighing around 200 g were packaged under natural (control) or modified atmosphere packaging (MAP) conditions (50% N2 – 50% CO2) and stored at 4 °C or 10 °C for up to 85 d. Prior to packaging, groups of cheese blocks were inoculated with one each of the following foodborne pathogens at around 104 log cfu/g: Listeria monocytogenes, Salmonella Typhimurium, Escherichia coli O157:H7 or Staphylococcus aureus, whilst further groups of cheese blocks were not inoculated. The protein, fat, moisture and salt contents as well as the pH of control and MAP cheese samples did not change significantly (P > 0.05) throughout 4 °C storage, while the pH values of control and MAP cheese samples were significantly (P < 0.05) reduced at 10 °C storage. At 10 °C storage, yeasts and molds, psychrotrophs and lactic acid bacteria (LAB) were significantly higher (P < 0.05) for the normal atmosphere than the MAP cheese samples after the 4th, 8th and 4th days, respectively. At 4 °C storage, the yeasts and molds or psychrotrophs were significantly higher (P < 0.05) than those of control after the 6th and 15th days, respectively at 4 °C storage. All foodborne pathogens showed a higher decrease (P < 0.05) at 10 °C than 4 °C storage. S. aureus proved more sensitive in inactivation in the MAP conditions than atmospheric conditions. L. monocytogenes and S. aureus presented a higher decrease than that of E. coli O157:H7 and S. Typhimurium. In conclusion, MAP proved efficient in retarding the growth of yeasts, molds, psychrotrophs and E. coli O157:H7, L. monocytogenes , S. Typhimurium and S. aureus in Graviera Agraphon cheese during refrigerated storage at 4 and 10 °C. [ABSTRACT FROM AUTHOR]

In the present study, novel silver nanoparticles (AgNPs) were synthesized via a green method by using Forsythia suspensa fruit water extract. The synthesized AgNPs showed antibacterial activities against all the tested food-borne pathogens, including Listeria monocytogenes , Vibrio parahaemolyticus , Escherichia coli O157:H7, Staphylococcus aureus , Pseudomonas aeruginosa and Salmonella typhimurium. Furthermore, the S. aureus and V. parahaemolyticus were introduced as Gram-positive and Gram-negative model strains to explore the antibacterial mechanism of AgNPs. Minimal inhibitory concentrations (MICs) of V. parahaemolyticus and S. aureus were 6.25 μg/mL and 50 μg/mL, respectively, and the minimum bactericidal concentrations (MBCs) of V. parahaemolyticus and S. aureus were 12.5 μg/mL and 100 μg/mL, respectively. Results indicated that the AgNPs caused morphological alterations and damaged the membrane integrity of strains S. aureus and V. parahaemolyticus. In addition, the AgNPs induced the release of nucleic acids of V. parahaemolyticus cells, resulting in disrupting of cells reproduction. Unlabelled Image • A novel green synthesis method of silver nanoparticles based on Forsythia suspensa fruit was explored. • The silver nanoparticles showed good antibacterial activity against all tested food-borne pathogens. • The silver nanoparticles caused visualized morphological alterations of food-borne pathogens. • The silver nanoparticles damaged membrane integrity of food-borne pathogens. • The synthesized silver nanoparticles can induce the release of the nucleic acids of Vibrio parahaemolyticus. [ABSTRACT FROM AUTHOR]

Essential oils extracted by hydro-distillation form date palm spathe (byproduct from date palm plants) were tested for their antibacterial activity against some food-borne pathogens. Listeria monocytogenes ATCC 7644, Staphylococcus aureus ATCC 29243, Salmonella enterica subsp. enterica serovar Enteritidis ATCC 13076 and E. coli ATCC 25922 were inhibited (11–13 mm inhibition zones) by spathe essential oils (SEOs) using the agar well assay (in vitro test). Staphylococcus aureus ATCC 29243 and E. coli ATCC 25922 were not detected in chicken meat treated with 1% (v/w) SEOs and subjected to abusive storage conditions (20 °C for 18 h). When treated with 0.5% SEO, counts of S. aureus and E. coli increased by only 0.2 and 0.7 log 10 cfu/g, respectively, compared to the initial inoculated level in meat samples stored at 20 °C for 18 h. SEOs possessed DPPH radical scavenging activity with IC 50 of 0.61 μg/ml. Forty one compounds were major constituents detected by GC–MS analysis of SEOs. 3,4-Dimethoxytoluene (38.12%) and 5,9-Undecadien-2-one (12.45%) were major compounds in extracted oils. Density and refractive index of SEOs were 0.987 and 1.5905, respectively. SOEs are added-value products from date palm, which could be employed in food industry and pharmaceuticals. The study is the first report on antibacterial activity of SEOs against L. monocytogenes ATCC 7644 and other standard food-borne pathogens in agar diffusion assay and food model (chicken meat). DPPH radical scavenging activity of SEOs has not previously been documented. • Essential oils (EOs) were extracted from a byproduct of Phoenix dactylifera L. • Spathe EOs (SEOs) inhibited test gram-positive and gram-negative pathogens. • 1% SEOs were bactericidal for Staphylococcus aureus and E. coli in chicken meat. • DPPH radical scavenging activity was demonstrated by SEOs. • SEOs may be an added value product employed in food industry and pharmaceuticals. [ABSTRACT FROM AUTHOR]

Background and Objectives: Traditional culture methods for detection of food-borne pathogens, a major public health problem, are simple, easily adaptable and very practical, but they can be laborious and time consuming. In this study, we eliminated culturing steps by developing a new separation method and therefore, decreased the detection time of food-borne pathogens (Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes) to a few hours. Materials and Methods: We used alkaline water and different alkaline buffers to elute bacteria from the lettuce surface as a model for ready-to-eat vegetables. Buffers used were as follows: 1) 0.05 M glycine; 2) 0.05 M glycine −100 mM Tris base −1% (w/v) beef extract; 3) buffer peptone water; 4) buffer phosphate saline. Buffers were adjusted to pH of 9, 9.5 and 10. In order to elute the bacteria, the lettuce pieces were suspended into buffers and shacked for 30, 45 and 60 min. Moreover, a multiplex PCR method for the simultaneous detection of food-borne pathogens was performed. Results: The results showed that buffer peptone water at pH 9.5 for 45 min have high ability to elute bacteria from the lettuce surface and the bacteria can be detected using multiplex PCR. Conclusion: We developed a new rapid and efficient method for simultaneous separation of food-borne pathogens. This method eliminates culturing stages and permits the detection and identification of target pathogens in a few hours. [ABSTRACT FROM AUTHOR]

The bio-preservative efficacy of a partially purified antibacterial peptide (ppABP) produced by Bacillus licheniformis Me1 in an economical medium developed using agro-industry waste was evaluated by direct application in milk and milk-based food products. The addition of ppABP in milk samples stored at 4 ± 2 °C and 28 ± 2 °C resulted in the growth inhibition of pathogens Listeria monocytogenes Scott A, Micrococcus luteus ATCC 9341, and Staphylococcus aureus FRI 722. The shelf life of milk samples with added ppABP increased to 4 days at 28 ± 2 °C, whereas curdling and off-odor were noticed in samples without ppABP. Furthermore, the milk samples with ppABP were sensorily acceptable. Antilisterial effect was also observed in cheese and paneer samples treated with ppABP. These results clearly indicate that the ppABP of B. licheniformis Me1 can be utilized as a bio-preservative to control the growth of spoilage and pathogenic bacteria, thereby reducing the risk of food-borne diseases. [ABSTRACT FROM AUTHOR]

Although lateral-flow test strip (LFTS) immunoassays are rapid and require no specialized equipment, they are less sensitive than culture and polymerase chain reaction (PCR)-based methods for detecting bacteria. This study compared the sensitivity of LFTS assays based on colloidal palladium nanoparticles (PdNPs) and colloidal gold nanoparticles (AuNPs). PdNPs demonstrated a time and concentration dependent oxidation of the horseradish peroxidase (HRP) substrate 3,3′,5,5′-tetramethylbenzidine (TMB), whereas AuNPs did not. PdNPs labeled HRP-conjugated antibody lateral flow test strip (PdNPs-HRP LFTS) assays were tested with 3,3′-diaminobenzidine (DAB), a water insoluble substrate. The sensitivity of PdNPs-HRP LFTS assays in detecting Listeria monocytogenes, Escherichia coli O157:H7 and Yersinia enterocolitica was 5–10-fold higher than that of AuNPs-based LFTS (AuNPs LFTS) assays. PdNPs-HRP LFTS assays of reduced milk inoculated with L. monocytogenes were more than 10-fold more sensitive than conventional AuNPs LFTS assays. These results suggest that the PdNPs-HRP LFTS immunoassay is a promising tool for ensuring food safety. [ABSTRACT FROM AUTHOR]

Chili peppers ( Capsicum spp.) may possess antibacterial properties and have potential to be used in foods as antimicrobial. The complete chili pepper extract should be evaluated to determine which compounds are responsible for the antimicrobial activity. Extraction of compounds from the pepper is completed using a solvent. The type of solvent used for extraction influences which compounds are isolated, therefore the best extraction method needs to be determined. The purpose of this study was to identify which solvent is most successful at extracting unknown antibacterial compounds from jalapeño peppers. Fresh jalapeño peppers were chopped, weighed, and blended with a solvent (sterilized hot water, 70% methanol, 95% methanol, 70% ethanol, or 95% ethanol) at a 1:1 ratio (g/g) until the mixture was homogenized, followed by shaking for 15 min. The slurry was centrifuged; supernatant was removed and used for antibacterial testing against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica. The diameter of growth inhibition was measured and statistically evaluated using ANOVA to determine the extract with the greatest antimicrobial activity. Solvents were tested alone as a control. There was greater bacterial inhibition from extracts created with methanol and ethanol than hot water. Listeria monocytogenes was significantly more susceptible to the extracts than E. coli or Salmonella isolates. Each solvent extract was then analyzed using high-performance liquid chromatography (HPLC) and fractions (A-G) were collected and used for subsequent disk diffusion analysis against L. monocytogenes. Fractions E and F (eluded between 20 and 30 min) exhibited the most antibacterial activity. There were no differences between solvents used ( p = .05). Further investigation into specific compounds within these extracts will be completed in the future. [ABSTRACT FROM AUTHOR]

Table olives are one of the most important fermented vegetables in the Mediterranean countries. Although this fermented vegetable has a long record of microbial safety, various studies have shown the presence of Listeria monocytogenes during table olive processing. This study focused on evaluating the behaviour of a cocktail of L. monocytogenes strains during fermentation of Spanish-style green Manzanilla olives. For this purpose, a challenge test consisting of artificial inoculation of olive fermentation with high levels of the food-borne pathogen (7.0 log 10 CFU/ml) was performed. The fermentation was carried out at the laboratory scale in sealed glass bottles (n = 168) under controlled conditions to avoid the initiation of lactic acid fermentation intentionally. This point was confirmed by the evolution of pH, which ranged from an initial 9.0 to final 6.0 units (decrease kinetic constant of −0.0016 h−1), as well as by the behaviour of lactic acid and mesophilic bacteria during the study (55 days). The fate of L. monocytogenes during fermentation was described using mathematical models, including the two-term Gompertz equation. During this time, the food-borne pathogen showed an initial growth phase which lasted until 250 h, reaching a maximum population level close to 9.0 log 10 CFU/ml, even in the presence of high salt concentrations (>6.0% NaCl). Then, a rapid decline phase was observed but continuously detecting a residual tail of around 2 log 10 CFU/ml. Data obtained in this work shows the importance of the control of olive fermentation, especially during the first weeks when pH is alkaline-neutral and environmental conditions could favour L. monocytogenes growth. • A challenge test with Listeria monocytogenes in olive fermentations was performed. • Inoculated Listeria monocytogenes during table olive storage decreased. • L. monocytogenes two-term Gompertz model was developed. • To reduce the risk of Listeria it is necessary to lower the pH during fermentation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A sensitive and specific ECL biosensor for Listeria monocytogenes was fabricated. • A zinc oxide-three-dimensional nitrogen-doped graphene composite was prepared. • The 3D porous structure provided a large surface area and loading capacity. • It reliably and effectively detects the content of Listeria monocytogenes in food. A novel electrochemical luminescence (ECL) sensor was fabricated by self-assembly of an amino-modified aptamer onto a zinc oxide-three-dimensional nitrogen-doped graphene composite (ZnO-3DNGH)-modified electrode surface for the measurement of Listeria monocytogenes (LM) levels. As introduced the nitrogen element into the graphene framework, the prepared 3DNGH porous nanomaterial provides better conductivity and a larger surface area for Ru(bpy) 3 2+. Meanwhile, ZnO served as the catalyst, which can effectively enhance the electrochemical performance. In optimal condition, the sensor exhibited a linear relationship between the luminescence signal (△I ECL) and the logarithm of LM concentration (C LM) over the range 15 CFU·mL−1 to 1.5 × 107 CFU·mL−1 with a correlation coefficient of 0.9904 and a limit of detection (S/N = 3) of 5 CFU·mL−1. The sensor was successfully demonstrated to be capable of measuring the level of LM in both pork and milk samples, with rates of recovery of 91.4%-104.2% as calculated by a standard addition method. The results of the study demonstrate that the novel sensor offers a new method of sensitive and selective measurement of LM in complex samples, with considerable potential for applications in the fields of food inspection, molecular diagnosis, and biotechnology. [ABSTRACT FROM AUTHOR]

We investigated the combination effect of ohmic heating and pH for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in orange juice. Juice of varying pH (2.5, 3.5, and 4.5) was inoculated with the pathogens and subjected to ohmic heating at different temperatures (50, 55, and 60 °C) for different times (from 0 to 60 s). The reduction of pathogens was higher as treatment temperature and time increased and juice pH decreased. At pH 2.5, populations of E. coli O157:H7 were reduced by > 1.81 log, to below the detection limit within 60, 30, and 20 s at 50, 55, and 60 °C, respectively. S. Typhimurium was reduced by 5.15 log within 60 s at 50 °C and to below the detection limit within 10 s at 55 and 60 °C. L. monocytogenes was little affected at 50 °C but was reduced by 2.15 and 3.37 log after 60 s treatment at 55 and 60 °C. There was a similar pattern of inactivation of the pathogens at pH 3.5 and 4.5. There were no significant quality changes after treatment. In conclusion, our results indicate that ohmic heating can effectively inactivate the pathogens and antimicrobial effect significantly increases when combined with higher acidity. [ABSTRACT FROM AUTHOR]

Propionicin PLG-1 is a bacteriocin produced by Propionibacterium thoenii P127. Such bacteriocin inhibits wide range of food-borne pathogens such as pathogenic Escherichia coli, Pseudomonas aeruginosa, Vibrio parahaemolyticus, Yersinia enterocolitica and a strain of Corynebacterium sp. In the present study, plg-1 gene expressing propionicin PLG-1 was isolated, sequenced for the first time and the resulting sequence was analysed using several web-based bioinformatics programs. The PCR product containing plg-1 gene was transferred to different lactic acid bacterial (LAB) strains using pLEB590 as a cloning vector to give the modified vector pLEBPLG-1. LAB transformants showed an antimicrobial activity against Esch. coli DH5α (most affected strain), Listeria monocytogenes 18116, and Salmonella enterica 25566 as model pathogenic strains. Such LAB transformants can be used in dairy industry to control the food-borne pathogens that are largely distributed worldwide and to feed schoolchildren in the poor countries where dangerous epidemic diseases and diarrhoea prevail. [ABSTRACT FROM AUTHOR]

Atmospheric pressure cold plasma technology is becoming increasingly popular for microbiological decontamination of food and bio-materials. In the present study, afterglow corona discharge air plasma (ACDAP) was used for the inactivation of most common food-borne pathogens, namely pathogenic Escherichia coli , Staphylococcus aureus , Salmonella typhimurium , Bacillus cereus , Listeria monocytogenes , and Vibrio parahaemolyticus . Corona discharge plasma was generated at an output voltage of 20 kV DC, and a frequency of 58 kHz. And, a centrifugal blower that provides an airflow velocity of 2.5 m/s at electrode tip level was used for generating the flowing afterglow of the plasma. During plasma exposure, about 20 °C rise in temperature and a 50% decrease in relative humidity were observed in a treatment chamber within 3 h of exposure. Upon ACDAP exposure, as high as 3.5-log (99.97%) reduction in viable cell counts of tested food pathogens, especially E. coli O157:H7, was observed over a 24-hour exposure. The pathogen inactivation pattern was better explained by using the Singh–Heldman model, which belongs to pseudo-first-order kinetics. In conclusion, ACDAP was shown to be effective for the inactivation of common food-borne pathogens. [ABSTRACT FROM AUTHOR]

Data relative to in situ Listeria monocytogenes inactivation in fermented sausages were collected from 13 individual studies found in the literature. Inactivation rates were extrapolated and used to develop a predictive model to evaluate the relative effects of pH, water activity (a w ) and temperature on L. monocytogenes fate during fermentation and ripening. Temperature explained ca. 60% of the data variability, while pH and a w only a small part. Temperature alone may not be sufficient to cause pathogen's inactivation, but inactivation rate is dominated by temperature when pH and a w are in the range which prevent L. monocytogenes growth. A predictive model based on two Arrhenius equations (ln[inactivation rate] = − 25.71 − [− 0.6829 / (8.314 × T)] for fermentation; and ln[inactivation rate] = − 44.86 − [− 1.219/(8.314 × T)] for ripening) was developed. The model can be used to quantify the effect of temperature and/or time changes on fermented sausage safety. The advantages and limitations of the model are discussed. [ABSTRACT FROM AUTHOR]

Aims: To evaluate synergetic effect of slight acidic electrolysed water (SAEW) and fumaric acid (FA) on inactivation of total viable count (TVC) and Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella Typhimurium in fresh beef and to study shelf life and sensory quality of beef. Methods and Results: Inoculated samples was dipped for 1, 3 and 5 min and immersed at 25, 40 and 60°C in SAEW, strong acidic electrolysed water (StAEW) and SAWE + FA. Treated meat was air-packaged and stored at 4 or 10°C. During storage, sampling was performed at 2-day intervals for microbiological and sensory changes. TVC was decontaminated at 40°C for 3 min by more than 3·70 log CFU g-1, and examined pathogens were reduced by more than 2·60 log CFU g-1 with SAEW + FA treatment. This treatment prolonged shelf life of beef meat up to 9 and 7 days when stored at 4 and 10°C, respectively. Conclusion: The combined treatment of SAEW + FA showed greater bactericidal effect and prolonged shelf life compared with individual treatments. Significance and impact of the study: Combined treatment of SAEW and FA can be a suitable hurdle technology reducing bacteria in fresh beef, substantially enhancing their microbial safety and decreasing pathogens growth during storage. [ABSTRACT FROM AUTHOR]

The NaCl MNICs (maximum non-inhibitory concentrations) and MICs (minimum inhibitory concentrations) for growth of various strains of six bacterial species were determined and then compared with those obtained for seven other solutes. The influence of prior growth conditions on the MNICs and MICs was also evaluated. No significant changes on the MNICs and MICs were found among the strains studied within each species. Among all factors investigated, only growth phase -for Gram-negatives- and growth at high NaCl concentrations led to a change in the NaCl MNICs. Species could be classified depending on its NaCl MNICs and MICs (in decreasing order) as follows: Staphylococcus aureus, Listeria monocytogenes, Cronobacter sakazakii, Enterococcus faecium, Escherichia coli and Salmonella Typhimurium. Similar results were obtained for KCl, LiCl, and sodium acetate, but not for the remaining solutes investigated (sucrose, glycerol, MgCl2 and CaCl2). Results obtained indicate that, in general, Gram-negatives showed lower MNICs and MICs than Gram-positives for all the solutes, S. aureus being the most solute tolerant microorganism. When compared on a molar basis, glycerol showed the highest MNICs and MICs for all the microorganisms -except for S. aureus- and LiCl the lowest ones. NaCl MNICs and MICs were not significantly different from those of KCl when compared on a molar basis. Therefore, the inhibitory action of NaCl could not be linked to the specific action of Na+. Results also showed that the Na+ tolerance of some species was Cl- dependent whereas for others it was not, and that factors others than aw-decrease contribute to the inhibitory action of LiCl, CaCl2 and MgCl2. [ABSTRACT FROM AUTHOR]

Abstract: A novel application of GeXP analyzer was developed for simultaneous detection of six pathogens associated with food poisoning outbreaks, including Salmonella enterica, Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus, Shigella spp., and Campylobacter jejuni. Chimeric primers containing both microbe- and pMD19-specific sequences were fused to universal sequences resulted in PCR products with intended sizes. The PCR products were separated by capillary electrophoresis and identified by using fluorescence spectrophotometry. Plasmid pMD19-T was added to each reaction as positive control to ascertain the PCR steps and data analysis step of the assay. The results indicate that the GeXP method is both specific and sensitive for the detection of all six food-borne pathogens in a single reaction-without any enrichment step. In conclusion, the GeXP-PCR assay is a rapid, sensitive and high-throughput method for parallel analysis of food-borne pathogens. [Copyright &y& Elsevier]

Abstract: Silver is known to inhibit microorganisms and therefore it is an ideal candidate for its incorporation in a wide variety of materials for food applications. However, there is still a need for understanding how silver prolonged exposure to bacterial contamination affects the bioavailability of the active silver species. In the present study, growth curves of Listeria monocytogenes and Salmonella enterica were performed for 3–5days in Tryptic Soy Broth (TSB) and M9 minimal medium (M9) in the presence of silver ions and silver solutions previously in contact with the growth media. The cultivability of the bacteria under these conditions was correlated with the viability of the bacterial populations as measured by flow cytometry analysis (FC) using a LIVE/DEAD BacLight kit. It was found that, after a period where viable counts were not detected, bacterial populations recovered and were able to proliferate in most cases. The resuscitation of the cultures was explained by both the existence of a resilient fraction of bacteria in a compromised state and the parallel inactivation of the silver species. This inactivation was found to be highly influenced by time dependant chemical reactions taking place in the environment of exposure, producing differences of at least 3 fold between results for nutrient rich environments and results for limiting environments. This study points out the need for understanding these chemical interactions and bacterial mechanisms of adaptation and may have relevance in the design of silver-based antimicrobial systems for food-related applications. [Copyright &y& Elsevier]

The antibacterial effects of Cinnamomum cassia essential oil (EO) and cinnamaldehyde were evaluated against single- and mixed-species cultivation of enteropathogenic Escherichia coli (EPEC) and Listeria monocytogenes attached to stainless steel. A central composite rotational design with two variables and eleven assays was used to optimize the concentrations (0.00-1.00% v/v for the EO and 0.00-0.80% v/v for cinnamaldehyde) and contact times (1-21 min). The models generated were validated, and the effectiveness of C. cassia EO and cinnamaldehyde was compared with that of commercially available chemical sanitizers. Cinnamaldehyde and C. cassia EO proved to be efficient alternatives to commercial chemical sanitizers in the reduction or elimination of sessile bacterial cells. The activity of these natural compounds was, in most cases, equivalent or superior to that of the chemical sanitizers tested. However, L. monocytogenes was more resistant than EPEC to C. cassia EO and cinnamaldehyde, and the bacterial association in mixed-species biofilms made them more susceptible to these compounds. [ABSTRACT FROM AUTHOR]

Abstract: NaCl is an important multifunctional ingredient applied in dry-cured ham elaboration. However, its excessive intake has been linked to serious cardiovascular diseases causing a recent increase in the development of reduced salt products. In the present study Listeria monocytogenes and Salmonella, food-borne pathogens which can cross-contaminate post processed products, were spiked with <100CFU/g on slices of both standard (S) and NaCl-free processed (F) (elaborated with KCl+potassium lactate instead of NaCl) smoked dry-cured ham. Although L. monocytogenes and Salmonella counts decreased faster in S ham, pathogens were present in both types of non-pressure treated ham during the entire refrigerated storage period (112days). Pressurisation at 600MPa for 5min caused the elimination of both pathogens in S ham after 14days. In contrast, Salmonella and L. monocytogenes were present in F ham until days 28 and 56, respectively, indicating that the NaCl-free processed dry-cured ham had lower stability than standard smoked dry-cured ham. [Copyright &y& Elsevier]

Abstract: 402 samples of 22 species of cultivated and wild fresh mushrooms sold in retail markets and supermarkets in Zaragoza (Spain) were studied to quantify their microbial load (mesophilic aerobic microorganisms, Pseudomonas genus, Enterobacteriaceae, lactic acid bacteria, total and thermotolerant coliform bacteria, Escherichia coli, yeasts and moulds) and to investigate the presence of E. coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Yersinia enterocolitica. The total microbial counts ranged from 4.4 to 9.4 log cfu/g, the genus Pseudomonas being the most prevalent with counts from 3.7 to 9.3 log cfu/g and Auricularia auricula-judae the species with the highest microbial load (9.4 log cfu/g). No significant differences (p > 0.05) were detected between mean counts of wild and cultivated species in all the microbial groups studied. The microbiological safety level of the cultivated mushrooms was excellent since no pathogens were isolated, and the microbial counts of indicator microorganisms were low, being detected in only half of the species. Salmonella spp, E. coli O157:H7 and S. aureus were not isolated from any sample, Y. enterocolitica was detected in only four samples of wild mushrooms whereas twenty-six (6.5%) were positive for L. monocytogenes, their occurrence being relatively high in Calocybe gambosa (40%), Hygrophorus limacinus (40%) and Tuber indicum (100%). These results suggest that a strategy to reduce bacterial populations, and to improve the microbiological safety of some species of fresh mushrooms, should be investigated. [Copyright &y& Elsevier]

Abstract: Ready-to-cook Iranian barbecued chicken consists of cubed chicken breast, lemon juice, salt, red pepper, onion, saffron and vegetable oil with an overall pH value of about 5.5. This product is sometimes consumed under-cooked, hence it may pose health hazards to consumers when contaminated with food-borne pathogens. In this study, the effect of gamma irradiation (0, 1.5, 3 and 4.5kGy) on the microbial quality of ready-to-cook (RTC) barbecued chicken samples stored at 4°C for 15 days was investigated. Moreover, the effectiveness of irradiation for inactivating Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella typhimurium inoculated into the samples was also studied. Irradiation of the samples resulted in dose dependent reduction in counts of aerobic mesophilic bacteria, yeasts and molds, Enterobacteriaceae and lactic acid bacteria. Among the microbial flora, yeasts and molds and Enterobacteriaceae were more sensitive to irradiation and got completely eliminated at dose of 3kGy. D 10 values of L. monocytogenes, E. coli O157:H7 and S. typhimurium inoculated into the samples were 0.680, 0.397 and 0.601kGy, respectively. An irradiation dose of 3kGy reduced the counts of E. coli O157:H7 to an undetectable level in RTC barbecued chicken but was ineffective on elimination of L. monocytogenes and S. typhimurium. However, none of the food-borne pathogens were detected in the samples irradiated at 4.5kGy. This study showed that irradiation had no undesirable effects on the initial sensory attributes of barbecued chicken. At the end of the storage period, irradiated samples were more acceptable compared to non-irradiated ones. [Copyright &y& Elsevier]

The antibacterial potential of essential oils and methanol extracts of sweet basil Ocimum basilicum L. (Lamiaceae) was evaluated for controlling the growth range of food-borne pathogenic bacteria. Essential oils extracted by hydrodistillation from the leaves and stems were analyzed by GC-MS. Fifty-seven compounds representing 94.9 and 96.1% of the total leaf and stem oils, respectively, were identified, of which methyl chavicol (36.7 and 29.9%), gitoxigenin (9.3 and 10.2%), trimethoquinol (10.3 and 8.4%), β-guaiene (3.7 and 4.1%), aciphyllene (3.4 and 3.0%), alizarin (3.2 and 4.4%), naphthaline (2.2 and 3.8%), (–)-caryophyllene (2.0 and 1.9%), and mequinol (1.6 and 1.8%) were the major compounds. The essential oils (10 μL/disc of 1:5, v/v dilution with methanol) and methanol extracts (300 μg/disc) of O. basilicum displayed a great potential of antibacterial activity against Bacillius cereus, B. subtilis, B. megaterium, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Shigella boydii, S. dysenteriae, Vibrio parahaemolyticus, V. mimicus, and Salmonella typhi with their respective zones of inhibition of 11.2–21.1 mm and MIC values of 62.5–500 μg/mL. The results of this study suggest that the natural products derived from O. basilicum may have potential use in the food and/or pharmaceutical industries as antimicrobial agents. [ABSTRACT FROM AUTHOR]

Abstract: The antimicrobial activities of edible coatings based on a tapioca starch/decolorized hsian-tsao leaf gum (dHG) matrix with various green tea extracts (GTEs) were evaluated. Its effect on the shelf-life extension of fruit-based salads, romaine hearts, and pork slices were investigated as well. Three types of GTEs from hot water (80°C) (W), 40% (E4) and 80% (E8) ethanol were prepared. It was found that all GTEs showed pronounced inhibition on Gram positive bacteria in agar media, including Staphylococcus aureus BCRC 10781, Bacillus cereus BCRC 11778 and Listeria monocytogenes BCRC 14848, but not on Gram negative bacteria, such as Escherichia coli DH10β and Salmonella enteria BCRC 10747. The antimicrobial activities increased with increasing GTEs concentration (1, 2 and 5%), but did not differentiate significantly in terms of the effect of extraction solvents. When various GTEs (1%) were added to an edible coating formulation based on 1.35% tapioca starch +0.15% dHG +0.225% glycerol, pronounced antimicrobial activity on Gram positive bacteria was also observed as evaluated by using cylinder diffusion and antimicrobial migration tests. It was believed that the active compounds in green tea extracts could leave the coating matrix and migrate to increase the non-growth area. When being sprayed on various real food models, all tapioca starch/dHG coatings containing GTEs could successfully reduce the aerobic counting and growth of yeasts/molds by 1 to 2 log cycles in fruit-based salads, as compared to the control sample. Furthermore, during refrigerated storage of romaine hearts and pork slices for 48h, tapioca starch/dHG coatings with E4 extracts demonstrated pronounced antimicrobial activity against Gram positive bacteria (4–6 log cycles reduction), followed by W extracts and E8 extracts in a decreasing order. Such results implied the high efficacy of antimicrobial migration of tapioca starch/dHG coatings containing GTEs and their application potentials on foods. [Copyright &y& Elsevier]

Abstract: This study was undertaken to examine the chemical compositions of essential oil and tested the efficacy of oil and organic extracts from seeds of Zizyphus jujuba against food-borne pathogens. The chemical compositions of the oil was analysed by Null. Twenty three compounds representing 91.59% of the total oil were identified. The oil (5μl of 1:5 (v/v) dilution of oil with methanol) and extracts of hexane, chloroform, ethyl acetate and methanol (300μg/disc) of Z. jujuba displayed a remarkable antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes ATCC 19166, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella typhimurium KCTC 2515 and Escherichia coli ATCC 8739. The scanning electron microscopic studies also demonstrated the effect of essential oil on the morphology of Staph. aureus ATCC 6538 at the MIC value, along with the potential effect on cell viabilities of the tested bacteria. [Copyright &y& Elsevier]

Abstract: Intoxications and infections caused by food-borne pathogens represent an increasing public health problem, and diagnostic tests in multiplex format are needed for the rapid identification of food contaminations caused by more than one microbial species. We have developed a multiple PCR-based platform for the simultaneous detection of the widespread milk-associated pathogens Salmonella spp., Listeria monocytogenes and Escherichia coli O157. The assay combines an enrichment step in a medium properly formulated for the simultaneous growth of target pathogens, a DNA isolation method, and a multiplex Real-Time PCR detection system based either on dual-labelled probes (mRT-PCR), or on melting curve analysis (mHRM). The second, producing a distinct peak for each amplification product, allows the qualitative assessment of pathogen presence. Moreover, the internal amplification control (IAC) included in the reaction, ensuring the reliability of results, complies with quality management programmes. Inclusivity and exclusivity were 100% each, with a detection limit of 1 CFU for each pathogen in a total of five 25 ml-aliquots of raw milk, and a duration of two working days. The assay represents an alternative approach for the qualitative detection of the cited bacterial species, suitable for a relatively inexpensive screening of several milk samples, reducing the turnaround time and the workload. [Copyright &y& Elsevier]

Abstract: The food-borne pathogens Listeria monocytogenes, Salmonella enterica, Staphylococcus aureus, Yersinia enterocolitica and Campylobacter jejuni, and the spoilage lactic acid bacteria (LAB), Escherichia coli and the yeast Debaryomyces hansenii were inoculated on slices of cooked ham, dry cured ham and marinated beef loin. During storage at 4°C, L. monocytogenes and LAB increased up to 3.5log units while the other species, unable to grow under refrigeration, continued at the spiking level. The application of a 600MPa treatment effectively inactivated most of the microorganisms, the counts of which, except for LAB that increased in cooked ham and in beef loin, progressively decreased or maintained below the detection limit during the whole storage (120 days at 4°C). [Copyright &y& Elsevier]

In this study, we examined the chemical compositions of essential oil and tested the efficacy of oil and organic extracts of Cestrum nocturnum L. against food-borne pathogens. The chemical compositions of the oil was analysed by gas chromatography-mass spectrometry (GC-MS). Forty-seven compounds representing 93.28% of the total oil were identified. The oil [5 μL of 1:5 (v/v) dilution of oil with methanol] and organic extracts of hexane, chloroform, ethyl acetate and methanol (300 μg per disc) of C. nocturnum displayed a great potential of antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes (ATCC 19166 and ATCC 15313), Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella typhimurium KCTC 2515 and Escherichia coli ATCC 8739. Also the oil had strong detrimental effect on the viable count of the tested bacteria. The results obtained from this study may contribute to the development of new antimicrobial agents with potential applications in food industries as natural preservatives to control food-borne pathogens. [ABSTRACT FROM AUTHOR]

In the food industry, the increasing antimicrobial resistance of food-borne pathogens to conventional sanitizers poses the risk of food contamination and a decrease in product quality and safety. Therefore, we explored alternative antimicrobials N-Acetyl-l-cysteine (NAC), rhamnolipids (RLs), and usnic acid (UA) as a novel approach to prevent biofilm formation and reduce existing biofilms formed by important food-borne pathogens (three strains of Salmonella enterica and two strains of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus). Their effectiveness was evaluated by determining minimum inhibitory concentrations needed for inhibition of bacterial growth, biofilm formation, metabolic activity, and biofilm reduction. Transmission electron microscopy and confocal scanning laser microscopy followed by image analysis were used to visualize and quantify the impact of tested substances on both planktonic and biofilm-associated cells. The in vitro cytotoxicity of the substances was determined as a half-maximal inhibitory concentration in five different cell lines. The results indicate relatively low cytotoxic effects of NAC in comparison to RLs and UA. In addition, NAC inhibited bacterial growth for all strains, while RLs showed overall lower inhibition and UA inhibited only the growth of Gram-positive bacteria. Even though tested substances did not remove the biofilms, NAC represents a promising tool in biofilm prevention. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria (LAB) are often utilized to control food-borne pathogens on produce and on cooked, fermented, or refrigerated meats. Most research to date has focused on the inhibition of Listeria monocytogenes, Escherichia coli O157:H7, Salmonella, Clostridium botulinum, and spoilage microorganisms. LAB are excellent candidates for reducing pathogen levels on foods because they inhibit the growth of these microorganisms through various mechanisms without causing unacceptable sensory changes. This review provides an up-to-date look at research directed at maximizing the use of LAB by selecting the most appropriate strains, by learning how to apply them to foods most effectively, and by gaining an understanding of the mechanism by which they inhibit pathogens. [ABSTRACT FROM AUTHOR]