ABSTRACT

This research work revealed the antimicrobial compounds present in lactic acid bacteria isolated from some traditionally fermented foods, ogi, ugba and yogurt and their antimicrobial activity against some selected food pathogens. A total of fifteen food samples consisting 5 each of ogi, ugba and yogurt were screened for lactic acid bacteria. Nine organisms were isolated from the food samples and characterized both phenotypically and genotypically using PCR amplification and 16SrRNA DNA sequencing which revealed that 2 of the isolates were Lactococcus spp, 5 Lactobacillus spp, 1 Bacillus spp and 1 Streptococcus spp. The genotypic characterization revealed that the lactic acid bacteria isolates Lactococcus lactissubsp lactis 0711XYBLS, Lactobacillus fermentum CS19, Lactococcus lactis and Lactobacillus fermentum were closely related at 99% evolutionary distance. Lactococcus lactis subsp  lactis 0711XYBLS and Lactobacillus fermentum CS19 were utilized for the sole purpose of this research to determine their antimicrobial potentials against selected food pathogens. The lactic acid bacteria isolates produced antimicrobial metabolites diacetyl, hydrogen peroxide and lactic acid at varying degrees. The selected latic acid bacteria isolates were tested against food pathogens and their clear zones of inhibitions were noted. Lactococcus lactis subsp lactis 0711XYBLS isolated from ogi showed the highest Gram positive and Gram negative food pathogens ranging from 18.67 ± 1.15 to 12.67 ± 0.57 and 16.33 ± 0.56 to 8.00 ± 6.08  respectively where as Lactobacillus fermentum CS19 showed Antimicrobial activity for Gram positive food pathogens at 16.00  ± 1.00  to 8.67 ± 1.15 and 15.33 ± 1.15 to 8.67 ± 0.57 in Gram negative food pathogens. A great statistical significant difference was recorded between the pathogens at a significant level of p≤0.05. However, both organisms portrayed a great deal of antimicrobial activity against the selected food pathogens and can serve as novel antimicrobial agents. These potentials can be harnessed in food industries on a large scale as biopresevatives instead of the use of chemical preservation which may pose detrimental health risk on its consumers