Effect of Varied Culture Conditions on Crude Supernatant (Bacteriocin) Production from Four <i>Lactobacillus</i> Species Isolated from Locally Fermented Maize (Ogi)

Abstract

This 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. The isolation and identification of LAB from fermented maize (Ogi) and the effect of varied culture conditions on crude supernatant production and activity was evaluated. 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 varying growth medium conditions. The crude supernatant production was tested at different physical and cultural conditions such as temperature (25, 30, 35 and 40°C), pH (5, 6, 7 and 8), sodium chloride (NaCl) concentration (2, 4, 6 and 8%) and incubation duration (12, 24, 48 and 72 hours). The optimum bacteriocin production judged by their different zones of inhibition of crude supernatant was recorded at temperature, 30°C and then 35°C. There were significant differences between all the incubation temperatures at P<0.05. Duration of incubation showed highest crude supernatant activity after 72 hours. Furthermore, optimal conditions for crude supernatant production were observed to be highest at pH 6.0 followed by 5.0 and then 2% NaCl concentration. There were significant differences between the zones of inhibition of crude supernatants produced against the indicator organisms at various media pH and salt concentrations at P<0.05. These crude supernatants may have a potential use in reducing contaminations during industrial processes, as food preservatives and may help in improving the gastro-intestinal tract by fighting off pathogenic bacteria.