Characterization and safety evaluation of two beneficial, enterocin-producing Enterococcus faecium strains isolated from kimchi, a Korean fermented cabbage. (April 2022)

• Record Type: Journal Article
• Authors: Valledor, Samantha Joy D.; Dioso, Clarizza May; Bucheli, Jorge Enrique Vazquez; Park, Yu Jin; Suh, Dong Ho; Jung, Eun Sung; Kim, Bobae; Holzapfel, Wilhelm Heinrich; Todorov, Svetoslav Dimitrov
• Is Part Of: Food microbiology. Volume 102(2022)
• Publication Date: 2022-04
• Subjects: Enterococcus faecium -- Listeria monocytogenes -- Enterococcus spp. -- Bacteriocins -- Probiotics; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2021.103886
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: Enterococcus faecium ST20Kc and ST41Kc were isolated from kimchi, a traditional Korean fermented cabbage. Bacteriocins produced by both strains exhibited strong activity against Listeria monocytogenes and various Enterococcu s spp., including 30 vancomycin-resistant enterococcal strains, but not against other lactic acid bacteria (LAB) on the evaluated test panel. The antimicrobials produced by the strains were found to be proteinaceous and stable even after exposure to varying pH, temperature, and chemicals used in the industry and laboratory processes. Antimicrobial activity of both strains was evaluated as bactericidal against exponentially growing cultures of L. monocytogenes ATCC® 15313™ and Enterococcus faecalis 200A. Based on tricine-SDS-PAGE, the molecular weights of the bacteriocins produced by the strains were between 4 and 6 kDa. Additionally, both strains were susceptible to antibiotics, including vancomycin, kanamycin, gentamycin, ampicillin, streptomycin, tylosin, chloramphenicol, clindamycin, and tetracycline. Adhesion genes, map, mub, and EF-Tu, were also detected in the genomes of both strains. With gastrointestinal stress induction, both strains showed high individual survival rates, and capability to reduce viable counts of L. monocytogenes ATCC® 15313™ and Enterococcus faecalis 200A in mixed cultures. Based on the metabolomics analysis, both strains were found to produce additional antimicrobial compounds, particularly, lactic acid, phenyllactic acid, and phenethylamine, which can be potentially involved in the antimicrobial interaction with pathogenic microorganisms. Highlights: Two bacteriocinogenic Enterococcus faecium strains were isolated from kimchi. Safety of the bacteriocinogenic strains was approved. Bacteriocins were partially characterized and different aspects of mode of action studied. Effect of bacteriocin producing strains on control of L. monocytogenes in model GIT system was evaluated. Metabolomic analysis of the cell free supernatants was applied for evaluation of the presence of key metabolites.