ANTIMICROBIAL PROPERTIES AND PROBIOTIC POTENTIALS OF LACTIC ACID BACTERIA ISOLATED FROM RAW BEEF IN IBADAN, NIGERIA

摘要

Lactic acid bacteria (LAB) are important microflora in raw meat and fermented meat products. They exhibit antagonistic activities against undesirable microorganisms and are highly valued for their probiotic properties. LAB associated with raw beef from two major abattoirs in Ibadan, Nigeria were assessed for antimicrobial activity and probiotic potential. Agar-spot assay showed that 8 of 23 LAB isolates inhibited the growth of at least one of Escherichia coli, Listeria monocytogenes, K. pneumoniae and S. aureus. Selected antibacterial isolates were identified based on API50CHL as Lactobacillus plantarum (3), Pediococcus pentosaceus (2) Lactobacillus paracasei (1), Leuconostoc lactis (1) and Carnobacterium sp. (1). Antimicrobial activities were revealed to be dependent on acidification and production of bacteriocin-like substances. Five LAB strains lowered the pH of medium to 4 within 24 h, with Leuconostoc lactis Csu12 broth culture having the lowest pH (3.04 ±0.08). Bacteriocin-like activity was displayed by six LAB strains against at least one indicator organism. The antibacterial isolates tolerated low pH and different bile concentration (0.5 and 1%). In addition, they showed different levels of hydrophobicity to xylene. Results from this study suggest the consideration of our resident LAB from meat as novel protective cultures and probiotic candidates in the food industry.