Production of bacteriocin in batch fermentation of dairy effluents by Lactobacillus acidophilus LA5 and Bifidobacterium animalis subsp. lactis BB12

The purpose of this study was to investigate the factors affecting the fermentation process in the production of bacteriosin by two commercial probiotic bacteria in dairy factories effluents as a culture medium. Therefore, the effect of independent variables, including incubation temperature (30, 34 and 38 °C), initial pH (5, 6 and 7), duration of incubation (12, 30 and 48 hours), yeast extract concentration (0, 2 and 4 %), probiotic bacterial species (L. acidophilus LA5 and B. animalis subsp. lactis BB12) and culture medium (cheese whey and milk permeate) was studied using a completely randomized design with two-level factorial arrangement. The results showed that the temperature and time of incubation as well as the culture medium had a significant effect on bacteriosin production (p<0.05). Also, temperature, yeast extract concentration, culture medium type and culture of bacteria had a significant effect on biomass (p<0.05). Initial pH and culture medium had a significant effect on total protein content (p<0.05). Based on the results of incubation temperature, duration of incubation, yeast extract concentration, type of culture medium and type of probiotic bacteria had a significant effect on the titratable acidity (p<0.05). The levels of bacteriosin activity, biomass, total protein, and titratable acidity were in the range of 1000 to 5000 AU/mL, 0.80 to 8.67 g/L, 107.75 to 351.92 mg/L and 0.25 to 1.41 g/L, respectively. In general, the results showed that cheese whey and L. acidophilus LA5 is the suitable culture medium and bacterium for producing bacteriosin, respectively.