Effect of Varied Culture Conditions on Bacteriocin Production of Four Lactobacillus species Isolated from Locally Fermented Maize (Ogi)
Background: Lactic acid bacteria (LAB) predominates the micro flora of fermented products. They produce metabolites that inhibit the growth of food borne pathogens and spoilage microorganisms. Aim: To isolate and identify LAB species from fermented maize (Ogi) and to determine the effect of varied culture conditions on bacteriocin production and antibacterial activity against indicator organisms. Materials and methods: Four (4) isolates of bacteriocin producing lactobacillus species (L. lactis, L. fermentum, L. casei and L. plantarum) with antibacterial activity against Salmonella typhimurium (ATCC 14028) and Shigella dysenteriae (ATCC 23351) were subjected to varied growth medium conditions. Bacteriocin production was tested at different physical and cultural conditions such as temperature (25, 30, 35 and 400C), pH (5, 6, 7 and 8), sodium chloride (NaCl) concentration (2, 4, 6 and 8%) and incubation duration (12, 24, 48 and 72 hours). Results: The optimum bacteriocin production judged by their different zones of inhibition was recorded at temperature, 300C and then 350C. There were significant differences between all the incubation temperatures at P<0.05. Duration of incubation showed highest bacteriocin activity after 72 hours. Furthermore, optimal conditions for bacteriocin production were observed to be highest at pH 6.0 followed by 5.0 and then in 2% NaCl concentration. There were significant differences between the zones of inhibition of bacteriocins produced against the indicator organisms at various media pH and salt concentrations at P<0.05. Conclusion: These bacteriocins may have a potential use as food preservative and may help in improving the gastrointestinal tract by fighting off pathogenic bacteria.
