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.

Human vitamin deficiencies still occur in many countries although most vitamins are present in a variety of foods, mainly because of malnutrition not only as a result of insufficient food intake but also because of unbalanced diets; this work screens some Lactic acid bacteria isolated from selected Nigerian fermented foods for vitamin (thiamine, riboflavin and niacin) production. Five lactic acid bacteria were isolated from selected Nigerian fermented foods (yoghurt, ogi, ogiri, ugba). The isolated lactic acid bacteria were identified based on cultural and biochemical characteristics. All the isolates were screened for thiamine, riboflavin and niacin production using microbiological assay. Thiamine, riboflavin and niacin produced were quantified.

Bacteriocins produced by various lactic acid bacteria (LAB) have found enormous use in the food industries as biopreservatives. This study evaluated the effect of varied culture conditions (temperature, pH, and NaCl concentration) on bacteriocin production by Lactococcus lactis MT186647 isolated from fermenting African oil bean seeds (Pentaclethra macrophylla Benth) using response surface methodology. A three-factor central composite design (CCD) was adopted with the interest of estimating the optimal conditions for its production using the response surface regression model, which evaluated the linear, squared, and interactive relationship between the response variables. The analysis of variance (ANOVA) using Minitab statistical software version 14.13 showed an R 2 = 0.869 variations in the response variable for culture conditions. It was accounted for by the predictors suggesting that the model was adequate. The optimal culture condition for bacteriocin production by L. lactis was estimated at 30.5°C, pH 5.9, 1.94% NaCl concentration at Y = 12.31 mm where Y represents the response (zone of inhibition) against Staphylococcus aureus ATCC 19095 using the agar well diffusion assay method. Validation of optimal values according to the regression model, produced an inhibition zone at Y = 13.33 ± 0.29 mm. There was a 19.33% increase in bacteriocin activity compared to an OFAT optimized medium from a previous study.