Antimicrobial profiles of probiotic lactic acid bacteria isolated from Nigerian fermented spice condiment Okpeye (<i>Prosopis africana</i>)

Abstract

Purpose: To investigate the antimicrobial profile of lactic acid bacteria (LAB), also called friendly bacteria or probiotics, found in Nigerian fermented spice condiment Okpeye (Prosopis africana). Methods: The LAB was isolated by enrichment and serial dilution. Biochemical characterization of isolates was done using standard microbiological protocols and determined using 16S rDNA gene sequencing. The survival of LAB in low pH 2.5 and 0.3 % bile salt media were evaluated. Using the agar well diffusion assay, the cell-free supernatant (CFS) standardized to 0.5 McFarland was evaluated for antibacterial, hydrogen peroxide, and bacteriocin activities to combat multi-drug resistant and foodborne pathogens (MDR-FBPs). Antibiotic susceptibility profile of isolates was profiled against seventeen antibiotics comprising twelve different classes using disk diffusion method. Results: Isolates identified were Pediococuss pentosaceus, Lactobacillus brevis, and Lactobacillus plantarum, with strong antibacterial activities against S. aureus, moderate activities against L. monocytogenes, and weak activities against P. aeruginosa, B. cereus, and E. coli. The isolate retained viability greater than 80 % at pH 2.5 and 0.3 % w/v bile condition after 4 h of exposure. The isolates showed a wide range of activities against MDR-FBPs. Regarding antibacterial activity, all isolates were effective against S. aureus, moderate against L. monocytogenes ATCC 13932, and weak against P. aeruginosa ATCC 27883, Bacillus cereus and E. coli. Conclusion: Okpeye is not just a spice; it contains high probiotics, which have antibacterial properties against foodborne and multidrug-resistant organisms, making it a beneficial addition to any diet.