• Food Science and Biotechnology
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• v.14 no.4
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• pp.503-508
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• 2005

Screening for antilisterial activity was performed in about three thousand isolates of lactic acid bacteria (LAB) from Chinese cabbage kimchi, and finally based on the relatively stronger antilisterial activities eight bacterial strains were selected. The bacteria were further characterized in terms of their tolerance to artificial gastric juice, pH 2.5, bile salts (0.3% oxgall), and to the different NaCl concentrations. Of the isolates, YK005 was especially investigated for its physiological characteristics due to its inhibitory activity against gram-positive Listeria monocytogenes as well as gram-negative Escherichia coli O157:H7, as they have been constantly reported to be resistant against bacteriocins produced by a number of LAB strains. YK005 was found to be rod-shaped, $3.8\;{\mu}m$ long ${\times}\;0.5\;{\mu}m$ wide, non-sporeforming, non-motile, catalase-negative, and produced gas from glucose (heterolactic). Based on the biochemical data obtained by API 50 CHL medium, the isolate was tentatively identified as Lactobacillus brevis. To validate the result obtained by the biochemical identification, rRNA-based PCR experiments using a pair of species-specific primers for L. brevis were conducted and a single band of 1400 bp was observed, which strongly indicated that YK005 belongs to L. brevis. The LAB isolates are potentially exploited as human probiotic organisms and are employed to control some food-borne pathogens like L. monocytogenes.

• Microbiology and Biotechnology Letters
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• v.44 no.3
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• pp.229-235
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• 2016

Korea has a long history of brewing traditional rice wine using a authentic starter culture called nuruk, which contains natural microbial flora. Because rice wine is consumed fresh without filtration, its viable cells contribute to the biological activities of the wine. In numerous studies, microbial strains isolated from rice wine have been screened for their functionalities, which were mainly probiotic properties and antimicrobial activities. Indeed, some lactic acid bacteria (LAB) were confirmed to have strong probiotic activities as well as other health-promoting effects. Moreover, some of the isolated probiotic strains produced functional compounds, such as exopolysaccharides and γ-aminobutyric acid. For antimicrobial activities, some LAB and yeast strains were identified to produce bacteriocins and killer toxins, respectively, with significantly broad spectrum of antimicrobial activity. These functional strains originating from traditional rice wine and their metabolites can be used directly for the production of value-added food products.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.184-188
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• 2002

A bacteriocin producing microorganism, which inhibits the growth of Lactobacillus sake, was screened and isolated from Kimchi. This microorganism was identified and named as Lactobacillus sp. Oh-B3, The maximum amount of bacteriocin was produced when the isolated microorganism was cultured in MRS media(pH 8.0) for 24 hours at 25℃. The bacteriocin from the isolated microorganism was purified through ammonium sulfate precipitation, dialysis and ultrafiltration. The bacteriocin was stable on the wide pH range of 2.0-9.0, and showed antimicrobial activity on some of gram positive bacteria, not on gram negative. The antimicrobial activity of bacteriocin was mostly removed by treatment of proteolytic enzymes. But, the bacteriocin was very stable on the heat treatment, and more than 50％ of activity was remained at autoclaving. The action mode of the bacteriocin showed bacteriocidal pattern, being same as that of general bacteriocins.

• Journal of Microbiology and Biotechnology
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• v.19 no.11
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• pp.1393-1400
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• 2009

A bacteriocin-producing strain PI80 was isolated from the gut of Penaeus indicus (Indian white shrimp) and identified as Streptococcus phocae PI80. The bacteriocin was purified from a culture supernatant to homogeneity as confirmed by Tricine SDS-PAGE. Reverse-phase HPLC analysis revealed a single active fraction eluted at 12.94 min, and MALDI-TOF mass spectrometry analysis showed the molecular mass to be 9.244 kDa. This molecular mass does not correspond to previously described streptococcal bacteriocins. The purified bacteriocin was named phocaecin PI80 from its producer strain, as this is the first report of bacteriocin production by Streptococcus phocae. The bacteriocin exhibited a broad spectrum of activity and inhibited important pathogens: Listeria monocytogenes, Vibrio parahaemolyticus, and V. fischeri. The antibacterial substance was also sensitive to proteolytic enzymes: trypsin, protease, pepsin, and chymotrypsin, yet insensitive to catalase, peroxidase, and diastase, confirming that the inhibition was due to a proteinaceous molecule (i.e., the bacteriocin), and not due to hydrogen peroxide or diacetyl. Phocaecin PI80 moderately tolerated heat treatment (up to $70^{\circ}C$ for 10 min) and resisted certain solvents (acetone, ethanol, and butanol). A massive leakage of $K^+$ ions from E. coli $DH5\alpha$, L. monocytogenes, and V. parahaemolyticus was induced by phocaecin PI80, as measured by Inductively Coupled Plasma Optical Emission Spectrometry (ICPOES). Therefore, the results of this study show that phocaecin PI80 may be a useful tool for inhibiting L. monocytogenes in seafood products that do not usually undergo adequate heat treatment, whereas the cells of Streptococcus phocae PI80 could be used to control vibriosis in shrimp farming.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.419-429
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• 2020

The problems caused by foodborne pathogens are not only a concern to the food industry but also with regard to global public health. Over the years, fermentation technology has proved to be one of the cheapest and safest methods for inactivating and controlling pathogenic microorganisms in food. Scientific evidence shows that lactic acid bacteria fermentation exerts significant antimicrobial effect against pathogenic bacteria and viruses. Lactic acid bacteria metabolites such as organic acids, bacteriocins and hydrogen peroxides have adverse effects on foodborne pathogens which lead to their inhibition. These compounds do not only cause physical injuries, but also have significant effects on the pathogens' gene expression. Furthermore, the presence of lactic acid bacteria in food provides nutritional competition among foodborne pathogens, and all these factors together suppress their growth. This study reviews our current knowledge of the antimicrobial abilities of lactic acid bacteria, their molecular mechanisms, and their application for inactivating foodborne pathogens.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.167-176
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• 2013

A novel bioactive molecule produced by Bacillus thuringiensis subsp. kurstaki Bn1 (Bt-Bn1), isolated from a common pest of hazelnut, Balaninus nucum L. (Coleoptera: Curculionidae), was determined, purified, and characterized in this study. The Bt-Bn1 strain was investigated for antibacterial activity with an agar spot assay and well diffusion assay against B. cereus, B. weinhenstephenensis, L. monocytogenes, P. savastanoi, P. syringae, P. lemoignei, and many other B. thuringiensis strains. The production of bioactive molecule was determined at the early logarithmic phase in the growth cycle of strain Bt-Bn1 and its production continued until the beginning of the stationary phase. The mode of action of this molecule displayed bacteriocidal or bacteriolytic effect depending on the concentration. The bioactive molecule was purified 78-fold from the bacteria supernatant with ammonium sulfate precipitation, dialysis, ultrafiltration, gel filtration chromatography, and HPLC, respectively. The molecular mass of this molecule was estimated via SDS-PAGE and confirmed by the ESI-TOFMS as 3,139 Da. The bioactive molecule was also determined to be a heat-stable, pH-stable (range 6-8), and proteinase K sensitive antibacterial peptide, similar to bacteriocins. Based on all characteristics determined in this study, the purified bacteriocin was named as thuricin Bn1 because of the similarities to the previously identified thuricin-like bacteriocin produced by the various B. thuringiensis strains. Plasmid elution studies showed that gene responsible for the production of thuricin Bn1 is located on the chromosome of Bt-Bn1. Therefore, it is a novel bacteriocin and the first recorded one produced by an insect originated bacterium. It has potential usage for the control of many different pathogenic and spoilage bacteria in the food industry, agriculture, and various other areas.

• Microbiology and Biotechnology Letters
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• v.47 no.2
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• pp.183-194
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• 2019

The consumption of fresh vegetables has been related to recurrent outbreaks of foodborne diseases (FBD) worldwide. Therefore, the development of effective alternative technologies is necessary to improve the safety of these products. This study aimed to isolate and identify epiphytic lactic acid bacteria (LAB) from fresh fruits and leafy vegetables and characterize their antagonistic capacity due to their ability to produce bacteriocins or antibacterial compounds. For this, 92 LAB isolates from fruits and leafy vegetables were screened for antagonistic activity. Two strains with the highest and broadest antagonistic activities were selected for further characterization; one from cantaloupe melon (strain CM175) and one from cilantro leaves (strain C15). The cell-free supernatants (CFS) of CM175 and C15 were found to exhibit antagonistic activity against FBD-causing pathogens. The CM175 and C15 strains were identified as Pediococcus pentosaceus and Lactobacillus graminis, respectively. Notably, the P. pentosaceus CM175 CFS stopped the growth of Salmonella Typhimurium, Salmonella Saintpaul, Staphylococcus aureus, and Listeria monocytogenes, and delayed Escherichia coli O157:H7 growth. Moreover, L. graminis C15 CFS delayed the growth of all indicator pathogens, but did not completely stop it. Organic acids and bacteriocin-like molecules were determined to be possibly exerting the observed antagonistic activity of the identified LAB strains. Thus, application of the antagonistic compounds produced by Pediococcus pentosaceus and Lactobacillus graminis could be a novel and ecological strategy in developing antimicrobial biopreservatives for the food industry and mitigating FBD by reducing the biological contamination in fruit and vegetable orchards, mainly via their potential in controlling both gram-negative and gram-positive pathogenic bacteria.

• Journal of Food Hygiene and Safety
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• v.36 no.6
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• pp.488-492
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• 2021

One of the well characterized bacteriocins, nisin, shows strong antimicrobial activity against pathogenic bacteria such as Listeria monocytogenes and Staphylococcus aureus. This study evaluated the synergistic effect of commercial nisin and SAP84 bacteriophage on S. aureus. Nisin showed antimicrobial activity against S. aureus KCTC 3881 in a dose-dependent manner. Eighteen IU/mL of the nisin decreased 4.03 Log CFU/mL of the strain in MRS broth after six hours compared with the controlled subject. On the other hand, the same dose of the nisin decreased 5.54 Log CFU/mL when co-treated with 0.1 MOI of the bacteriophage SAP84. Furthermore, the combination of nisin and SAP84 was successfully applied for controlling the S. aureus strain in lettuce.

• Microbiology and Biotechnology Letters
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• v.51 no.4
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• pp.353-373
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• 2023

Kimchi is a traditional Korean dish made with salted fermented vegetables and contains various nutrients and functional substances with potential health benefits. The fermentation process used to make kimchi creates chemical changes in the food, developing nutrients and functional substances that are more easily absorbed and enhanced by the body. Recent studies have shown that several lactic acid bacteria strains isolated from kimchi exhibit probiotic properties and have several health benefiting properties such as such as anticancer, anti-obesity, and anti-constipation; they also promote colon health and cholesterol reduction in in vitro and in vivo experiments, as well as in epidemiological cohort studies. Kimchi contains prebiotics, non-digestible fibers that nourish beneficial gut bacteria; therefore, its intake effectively provides both probiotics and prebiotics for improved gut health and a fortified gut-derived immune system. Furthermore, fermentation of kimchi produces a variety of metabolites that enhance its functionality. These metabolites include organic acids, enzymes, vitamins, bioactive compounds, bacteriocins, exopolysaccharides, and γ-aminobutyric acid. These diverse health-promoting metabolites are not readily obtainable from single food sources, positioning kimchi as a valuable dietary option for acquiring these essential components. In this review, the health functionalities of kimchi ingredients, lactic acid bacteria strains, and health-promoting metabolites from kimchi are discussed for their properties and roles in kimchi fermentation. In conclusion, consuming kimchi can be beneficial for health. We highlight the benefits of kimchi consumption and establish a rationale for including kimchi in a balanced, healthy diet.

• Journal of Animal Science and Technology
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• v.49 no.5
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• pp.621-632
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• 2007

The aim of this study was to isolate and characterize bacteriocin-producing bacteria from the intestine of duck to use as probiotics for livestock. A total of 416 strains were isolated from the small intestine and cecum of ducks and 13 isolates were finally selected after determinging inhibitory activity against pathogenic indicators by spot-on-lawn method. The selected strains were identified as Lactobacillus salivarius JWS 58, Lactobacillus plantarum JWS 1354, Pediococcus pentosaceus JWS 939, 7 strains of enterococci, and 3 strains of Escherichia coli. Lact. salivarius JWS 58, Ent. faecium JWS 833, and Ped. pentosaceus JWS 939 showed a strong inhibitory activity against Listeria monocytogenes. E. coli JWS 108 inhibited the growth of E. coli and Staphylococcus aureus. Lact. salivarius JWS 58 strain survived almost 50% in pH 2.5 phosphate buffer for 2 hr. Ped. pentosaceus JWS 939 and Lact. plantarum JWS 1354 showed strong amylolytic activity. These results suggest that a combination of bacteriocins or multispecies probiotics of the selected strains has a strong potential of alternative to antibiotics in livestock production.