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Bacteriocin produced by Bacillus subtilis SN7 was purified and characterized. This bacteriocin showed stability over a wide range of pH (3.0–9.0), heat, and solvent treatments. The bacteriocin was digested completely by protease and peptidases, but not by α-amylase or lipase. Bacteriocin showed strong antibacterial activities against Gram-positive bacteria, especially B. cereus , but not Gram-negative bacteria. The bacteriocin was purified using preparative-high performance liquid chromatography. Amino acid sequence of the purified bacteriocin was determined to be LGPQLNKGCATCSIGAACLVDGPIPDEIAG (MW 3400). The bacteriocin was confirmed as a novel bacteriocin through a homology search, deposited into NCBI protein blast (NO. PRJNA 309888), and designated as mejucin. Mejucin showed bactericidal effects on B. cereus , which led to irreversible alteration of the cellular membrane as well as leakage of intracellular constituents of B. cereus . These results suggest that mejucin has promising potential as a food preservative in the food industry. [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]

Sugar beet molasses contains natural components which can significantly inhibit the growth of food-borne pathogens, however, its antimicrobial mechanism has not yet well understood. In the present study, the antibacterial mechanism of sugar beet molasses polyphenols on S. aureus , L. monocytogenes , E. coli and S. typhimurium investigated by SDS-PAGE, SEM and TEM analysis. The sugar beet molasses polyphenols showed bacteriostatic activity against the growth of four food-borne pathogens. Meanwhile, sugar beet molasses polyphenols resulted in leakage of proteins of the four food-borne pathogens cells. Results of SDS-PAGE, SEM and TEM suggested that the antibacterial mechanism may be due to the damaged cytoplasmic membrane and bacterial proteins by sugar beet molasses polyphenols, and the sugar beet molasses polyphenols might change bacterial cells physiology and morphology. [ABSTRACT FROM AUTHOR]

Lime oil has recognized fungicidal and antibacterial properties. Nanoparticles and nanocapsules are structures that have been developed to overcome the high volatility of essential oils. Chitosan nanoparticles and chitosan nanocapsules incorporated with lime essential oil were synthesized by nanoprecipitation and nanoencapsulation methods, respectively. The samples were characterized by transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR), and Z potential was measured. Also, particle size distribution was analyzed by dynamic light scattering (DLS) and the antibacterial activity was studied. According to TEM, the average size of nanocapsules was higher than for nanoparticles. When lime essential oil was incorporated, the particle size increased. Lime essential oil incorporation was evidenced by FTIR. Chitosan nanocapsules showed higher Z potential value compared to chitosan nanoparticles. The antibacterial activity was tested against four food-borne pathogens, being higher for nanoparticles than for nanocapsules. The highest antibacterial activity was observed for chitosan nanoparticles incorporated with lime essential oil applied against Shigella dysenteriae , attaining an inhibition halo (IH) value of 3.5 cm for 40 μL of minimum inhibitory volume (MIV). The novelty of incorporating lime essential oil into chitosan nanoparticles and nanocapsules and the study of their enhancing effect on antibacterial activity are shown in this paper. [ABSTRACT FROM AUTHOR]

This work aimed to evaluate antioxidant and antimicrobial activity and action of selected wild berry (Rubus coreanus) for utilization. Wild berry was detected with rich non-enzymatic antioxidants (carotenoid, flavonoid, phenolic, anthocyanin, glutathione and ascorbic acid), and high activity antioxidant enzymes (superoxide dismutase, peroxidase, catalase, glutathione peroxidase and ascorbate peroxidase). Berry extract showed good radical scavenging capacity with low EC 50 values of ABTS, DPPH, reducing power, ferric reducing antioxidant power, oxygen radical absorbance capacity and total antioxidant capacity (6.25, 8.16, 6.13, 3.25, 8.75 and 6.31 μg/mL respectively), high scavenging effect for •OH, O 2 •− and H 2 O 2 at 100 μg/mL (95.28, 96.55 and 99.57%, respectively), and good potential to control foodborne pathogens. Antibacterial action was conducted on temporal changes for antibacterial curve, content leakage, oxidative stress, protein carbonyl, and respiratory-metabolic enzymes in Salmonella enteritidis exposed to berry extract at different concentrations (1/2-2 × MIC) and times (0–24 h), revealing that berry extract could act as an inducer for oxidative stress of S. enteritidis , causing cell structure damage and metabolic capacity deficiency. All findings indicated that wild berry could be as natural source of antioxidant or antimicrobial. • Wild berry contains rich enzymatic and non-enzymatic antioxidants. • Wild berry exhibits good antioxidant and antimicrobial effects. • Great potential of wild berry extract to control foodborne pathogens. • Wild berry can be as novel natural agent for food preservation. [ABSTRACT FROM AUTHOR]

The objective of the current study is to identify the influence of acidity on ohmic heating compared to conventional heating for inactivation of food-borne pathogens in orange juice. For conventional heating, the heating rate was not significantly different ( P > 0.05) regardless of pH and pathogens were inactivated more effectively at lower pH. However, different patterns were observed for ohmic heating. Although temperature and electrical conductivity were not greatly affected by lowering pH, temperature increased more rapidly with increasing pH due to higher electrical conductivity. Also, the inactivation patterns were significantly different ( P < 0.05) from conventional heating. While Salmonella Typhimurium was inactivated most rapidly at pH 2.5, Escherichia coli O157:H7 and Listeria monocytogenes were inactivated most rapidly at pH 4.5. When pathogens were exposed to each heating method at a fixed temperature, additional effects of ohmic heating were not observed. Also, the overall quality of orange juice subjected to ohmic heating was not greatly affected at any pH level. Therefore, increasing as well as lowering pH can also be considered effective ways to optimize pasteurization of orange juice when using ohmic heating. The different characteristics of ohmic heating compared to conventional heating indicate the necessity of a new approach. [ABSTRACT FROM AUTHOR]

The increasing market of probiotics from plant matrices justifies the interest on fermented olives – not only for their nutritional properties, but also because they contain health-promoting phytochemicals (such as phenolic compounds) that exhibit antibacterial, antiproliferative, anticarcinogenic and anti-inflammatory properties. Additionally, olives have proven a good source and carrier of Lactobacillus strains with probiotic characteristics. However, studies focusing on the combined effect of phenolic compounds with wild probiotic bacteria have not been yet carried out. Hence, the aim of this work was to set up the combination of native olive phenolic compounds, e.g. oleuropein and hydroxytyrosol, on the recommended levels for a daily dose of olives containing probiotic bacteria – and their effect on the attachment ability and action against pathogens in situ . Tests on the health benefits of these compounds, viability and adhesion capacity of probiotic bacteria, and consequent biofilm formation, composition and relationship with adhesivity on Caco-2 model were performed. The Caco-2 cell viability results (>140%) show that there is no toxicity effect of both phenolic compounds for the levels considered (0.04 and 0.01%, w/v, for OL and HT, respectively). Conversely, these compounds can inhibit (26–50%) proliferation of human colon adenocarcinoma cells. It became clear that biofilm production on abiotic surfaces is not necessarily associated with adhesivity on biotic surfaces. The strong increase in the adhesion degree of Lactobacillus plantarum 33 after biofilm establishment prompted evaluation of the correlation between biofilm formation and adhesion capacities. [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]

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]

Safflower (Carthamus tinctorius) and bitter melon (Momordica charantia L.) ethanolic extracts for controlling growth of fish spoilage bacteria (Acinetobacter lwoffii, Pseudomonas oryzihabitans, Enterobacter cloacae, Shigella spp., Morganella psychrotolerans and Photobacterium phosphoreum) and food-borne pathogens (Staphylococcus aureus, Klebsiella pneumoniae and Salmonella Paratyphi A), and their biogenic amine production were examined in anchovy infusion decarboxylase broth (AIDB). Bacterial load in AIDB was between 8.1 and 8.9 log CFU/ml. Bitter melon generally restricted growth of bacteria (p < 0.05). Bacterial load in the medium was not associated well with biogenic amine production. All bacteria had a high ability to form biogenic amines in AIDB. Significant discrepancies were noticed among groups in ammonia and biogenic amine production by bacteria (p < 0.05). A. lwoffii and P. phosphoreum were main bacteria produced the highest level of histamine (254.05 vs. 234.39 mg/L). Among food-borne pathogens, S. aureus was found stronger tyramine producer, with value of 736.53 mg/L. Bitter melon and safflower extract led approximately 9 and 12 fold lower histamine accumulation by S. aureus. The study result showed that bitter melon extract had more obvious effect, particularly for suppressing ammonia and toxicologically important biogenic amines production by bacteria, and thus could be suitable antimicrobial agent in food systems. • All bacteria of this work had a high ability to form biogenic amines in AIDB. • A. lwoffii and P. phosphoreum were main bacteria produced the highest level of histamine. • Among food-borne pathogens, S. aureus was main tyramine producer in AIDB. • Histamine accumulation in AIDB was generally higher in control groups than treated group (p < 0.05). • Bitter melon extract restricted ammonia and toxicologically important biogenic amines production by bacteria. [ABSTRACT FROM AUTHOR]

The present research was designed with an aim to attempt enhancement of antimicrobial efficacy of bacteriocins against food-borne pathogens. Bacteriocin Bac23 was extracted from a lactic acid bacterium which was isolated from raw milk, and identified as Lactobacillus plantarum using 16S rRNA gene sequencing. The purified Bac23 was found to be stable over a broad temperature (20 °C - 100 °C) and pH (2–12) range, its molecular weight was estimated as 5.1 kDa using SDS-PAGE, and the amino acid sequence determined using LCMS/MS identified it as plantaricin. Bac23 exhibited antimicrobial response against only three (S.flexneri , S.aureus , and P.aeruginosa) out of a total of six test food-borne pathogens. The purified Bac23 was further used for green synthesis of bacteriocin-capped silver nanoparticles (SNPs), which displayed a particle size of 31 nm and a hydrodynamic diameter of 79.19 nm. The capped SNPs exhibited an antibacterial response against all the six test food-borne pathogens displaying MIC value as low as 4 μg/ml for S.flexneri and P.aeruginosa ; thus, resulting into an almost 50% increase in the antimicrobial spectrum when compared with the antimicrobial activity of Bac23 alone. The present study therefore reports that the capping of a bacteriocin onto silver nanoparticles can enhance its antimicrobial response; hence aiding in combating food-borne pathogens. • Bacteriocin Bac23 was extracted from Lactobacillus plantarum PKLP5 isolated from raw milk. • LCMS/MS and SDS-PAGE identified Bac23 as plantaricin with molecular weight of 5.1 kDa. • Bac23-capped silver nanoparticles (SNPs) were synthesized using green synthesis approach. • TEM, DLS and Zeta potential analysis confirmed mono-dispersed nature and stability of capped SNPs. • Bac23-capped SNPS exhibited enhanced antimicrobial efficacy against test food-borne pathogens. [ABSTRACT FROM AUTHOR]

In the study, improvement in antibacterial properties of grapefruit peel essential oil after the nanoemulsification process was investigated. The essential oil composition was characterized using GC-MS, with d -Limonene being the main identified compound (82.86%). The antibacterial properties against common food-borne pathogens (Staphylococcus aureus, Enterococcus faecalis, Klebsiella pneumonia and Salmonella Paratyphi A) as well as 6 fish-spoilage bacteria isolated from 4 spoiled fish species: mackerel, sardine, anchovy and rainbow trout, have been evaluated using paper disc diffusion, MIC and MBC methods. The grapefruit peel essential oil showed bacteriostatic properties against the majority of tested bacterial strains, however, only the growth of Salmonella parathypi A, Vibrio vulnificus and Seratialique faciens was inhibited by the essential oil in the concentration up to 25 mg/mL. Incorporation of essential oil into the nanoemulsion system resulted in increased bacteriostatic potency when the oil concentration in the nanoemulsion were considered, however, no bactericidal effect was observed, which was probably due to too low concentration of essential oil in the nanoemulsion system. The improvement in the nanoemulsion preparation method and formulation should be investigated to further improve its antibacterial properties. • Antimicrobial properties of grapefruit peel EO and its nanoemulsion were investigated. • The analyses were carried on 4 food-borne pathogens and 6 fish-spoilage bacteria. • Grapefruit peel EO showed bacteriostatic effect against most studied bacteria strains. • Nanoemulsion showed bacteriostatic effect against some tested strains. • No bactericidal properties were observed for grapefruit peel EO and its nanoemulsion. [ABSTRACT FROM AUTHOR]

Consumption of food contaminated with microorganisms may lead to the public health issue. Therefore, it is important to monitor pathogenic microorganisms at the early stage of production to prevent loss in health and economic aspects. In this study, Raman spectroscopic technique was developed to identify food-borne pathogens. The results demonstrated that the variations of each bacterial spectra fingerprint were related to the physiological state of microorganism species. Moreover, the cultivation state of bacteria could affect the identification efficacy by this technique. The spectral ranges of 500–1600 cm−1 were selected to be analyzed with multivariate chemometric analysis and the principal component analysis (PCA) was used to determine optimal parameters for discrimination of food-borne pathogens. Calculated first and second principal components (PC1, PC2) accounted for 51.18 and 48.28% of total variance in the spectra were able to identify the food-borne pathogens at solid and aqueous states. It was clearly demonstrated that suitable cultivation state for microbiological detection by the developed condition was in an aqueous phase. In conclusion, this study suggested that Raman spectroscopy with near-IR wavelength excitation could be potentially useful for the rapid identification of bacteria and possibly applied for food quality control. • Raman spectroscopy has been developed to identify food-borne pathogens. • Raman scattering coupled with multivariate analysis differentiate bacterial species. • This method could reduce time-consuming and cost by simply using Aluminum materials. [ABSTRACT FROM AUTHOR]

The anti-microbial activity of crude extracts (hexane, acetone, ethanol, and aqueous) of 46 edible plants from Odisha, India, was studied using a broth microdilution assay against 8 common food-borne pathogens (Gram-positive: Bacillus cereus, Streptococcus faecalis, Listeria innocua, Micrococcus luteus, and Gram-negative: Escherichia coli , Pseudomonas aeruginosa , Salmonella enterica , Shigella sonnei). In total, 46 plant species belonging to 31 families were tested, from which 10 plants (22%) showed broad-spectrum in vitro antimicrobial activity (inhibiting at least two Gram-positive and Gram-negative species), while 28 (60%) exhibited narrow-spectrum activity against only Gram-positive -, and 2 (4%) against only Gram-negative bacteria. The Gram-positive pathogens were thus clearly more susceptible to most extracts compared to Gram-negative species. Selected active plant extracts were tested for their cytotoxicity against rhabdosarcoma (RD) and Vero cell lines. Selected extract(s) were further subjected to Thin layer chromatography (TLC) to determine their phytochemical profile; the extracts were largely distinguished by the presence of different phytoconstituents like phenols, flavonoids, tannins, saponins, steroids and terpenes. This preliminary antimicrobial screening showed that some edible Indian plants with antibacterial properties have potential as herbal preservatives in the food industry, and perhaps also as alternative therapeutic agents, particularly against food-borne bacterial diseases. • The antimicrobial activity was studied of 46 plants against 8 food-borne pathogens. • Ten plants showed broad-spectrum -, while 28 exhibited narrow-spectrum activities. • Fourteen plant extracts showed cytotoxicity against both RD and Vero cell lines. • Ten edible plants have potential as herbal preservatives in the food industry. [ABSTRACT FROM AUTHOR]