Aims: Screening and partial characterization of a bacteriocin produced by Pediococcus pentosaceus K23-2 isolated from Kimchi, a traditional Korean fermented vegetable. Methods and Results: A total of 1000 lactic acid bacteria were isolated from various Kimchi samples and screened for the production of bacteriocin. Pediocin K23-2, a bacteriocin produced by the Pediococcus pentosaceus K23-2 strain, showed strong inhibitory activity against Listeria monocytogenes. The bacteriocin activity remained unchanged after 15 min of heat treatment at 121°C or exposure to organic solvents; however, it diminished after treatment with proteolytic enzymes. The bacteriocin was maximally produced at 37°C, when the pH of the culture broth was maintained at 5·0 during the fermentation, although the optimum pH for growth was 7·0. The molecular weight of the bacteriocin was about 5 kDa according to a tricine SDS-PAGE analysis. Conclusions: Pediococcus pentosaceus K23-2 isolated from Kimchi produces a bacteriocin, which shares similar characteristics to the Class IIa bacteriocins. The bacteriocin is heat stable and shows wide antimicrobial activity against Gram-positive bacteria, especially L. monocytogenes. Significance and Impact of the Study: Pediocin K23-2 and pediocin K23-2-producing P. pentosaceus K23-2 could potentially be used in the food and feed industries as natural biopreservatives, and for probiotic application to humans or livestock.

This study was conducted to isolate and characterize bacteriocin-producing bacteria against Clostridium perfringens (C. perfringens) from domestic animals to determine their usefulness as probiotics. Bacteriocin-producing bacteria were isolated from pig feces by the spot-on-lawn method. A total of 1,370 bacterial stains were isolated, and six were tentatively selected after identifying the inhibitory activity against the pathogenic indicator C. perfringens KCTC 3269 and KCTC 5100. The selected strains were identified as Enterococcus faecalis (E. faecalis) by 16s rRNA sequencing. Most of the isolated bacterial strains were resistant to 0.5% bile salts for 48 h and remained viable after 2 h at pH 3.0. Some E. faecalis also showed strong inhibitory activity against Listeria monocytogenes KCTC 3569, KCTC 3586 and KCTC 3710. In the present study, we finally selected E. faecalis AP 216 and AP 45 strain based on probiotic selection criteria such as antimicrobial activity against C. perfringens and tolerance to acid and bile salts. The bacteriocins of E. faecalis AP 216 and AP 45 strains were highly thermostable, showing anticlostridial activities even after incubation at 121℃ for 15 min. These bacteriocinproducing bacteria and/or bacteriocins could be used in feed manufacturing as probiotics as an alternative to antibiotics in the livestock industry.

This study aimed to survey the antimicrobial resistance profiles of 690 pathogenic Escherichia coli isolates obtained from Korean pigs with symptoms of enteric colibacillosis between 2007 and 2017, while assessing the change in antimicrobial resistance profiles before and after the ban on antibiotic growth promoters (AGPs). Following the Clinical and Laboratory Standards Institute guidelines, the antimicrobial resistance phenotype was analyzed through the disk diffusion method, and the genotype was analyzed by the polymerase chain reaction. After the ban on AGPs, resistance to gentamicin (from 68.8% to 39.0%), neomycin (from 84.9% to 57.8%), ciprofloxacin (from 49.5% to 39.6%), norfloxacin (from 46.8% to 37.3%), and amoxicillin/clavulanic acid (from 40.8% to 23.5%) decreased compared to before the ban. However, resistance to cephalothin (from 51.4% to 66.5%), cefepime (from 0.0% to 2.4%), and colistin (from 7.3% to 11.0%) had increased. We confirmed a high percentage of multidrug resistance before (95.0%) and after (96.6%) the ban on AGPs. The AmpC gene was the most prevalent from 2007 to 2017 (60.0%), followed by the blaTEM gene (55.5%). The blaTEM was prevalent before (2007–2011, 69.3%) and after (2012–2017, 49.2%) the ban on AGPs. These results provide data that can be used for the prevention and treatment of enteric colibacillosis.

Do KH, et al. J Vet Sci. 2019 Jan;20(1):43-50. https://doi.org/10.4142/jvs.2019.20.1.43