Isolation, characterization and antibiotic resistance of lactic acid bacteria from dairy and seafood sources

In this study, isolation, characterization and antibiotic resistance of lactic acid bacteria (LAB) strains from seafood, milk and cheese were investigated. 128 LAB selected from approximately 1000 LAB isolated from food samples, were identified through phenotypic, morphological, genetic, and biochemical examinations. The identified LAB genera included lactobacilli, enterococci, lactococci, streptococci, leuconostoc, pediococci, and weisella. Raw goat's milk was dominated by lactobacilli and enterococci, with a notable presence of lactococci and weissella. Cheese samples were mainly dominated by lactobacilli, while fish samples predominated enterococci and leuconostoc. Weissella was the least abundant genus, mainly found in dairy products. Notably, the genera of Lactobacilli contained Lactobacillus rhamnosus, L. paracasei subsp. paracasei, L. brevis, L. sunkii, L. zeae, and L. casei; enterococci contained E. hirae, E. faecalis, E. lactis, E. faecium, E. gallinarum, E. durans, and E. casseliflavus; weisella contained W. cibaria and W. confusa; lactococci contained Lactococcus lactis subs. Lactis and L. lactis subs. cremoris; and leuconostoc contained L. mesenteroides subsp. mesenteroides. The result showed that significant resistance among LAB strains was observed in antibiotic susceptibility testing against 11 standard antibiotics. The weisella were the most resistant to vancomycin, tetracycline, rifampicin, penicillin, ampicillin and gentamycin. All enterococci showed resistance to all antibiotics. Leuconostoc were resistant to ampicillin, streptomycin, gentamicin and kanamycin. In particular, all lactobacilli became resistant to ampicillin followed by streptomycin. These results highlighted the antimicrobial resistance, diversity and distribution of LAB in different food matrices, highlighting their impact on food safety, public health and functional properties.