Optimization of Culture Conditions for Bacteriocin Production by Soil Isolates Pediococcus pentosaceus LB44 and Weissella confusa LM85

Abstract

Background: Bacteriocins are antimicrobial proteins or peptides secreted in the culture medium during the growth of bacteria. Bacteriocin production is influenced by various physical parameters such as pH, temperature, NaCl concentration, and carbon source. Objectives: The current study aimed at optimizing the culture conditions for higher growth and production of bacteriocins by the soil isolates, Pediococcus pentosaceus LB44, and Weissella confusa LM85. Methods: Growth of LB44 and LM85 isolates was measured spectrophotometrically at OD600 and bacteriocin production was determined in terms of growth inhibition zone using agar well diffusion assay (AWDA) at different pH (3.0 to 10.0), temperatures (30 to 50°C), NaCl concentrations (2% to 10%), and different concentrations (10 to 40 g/L) of carbon sources, glucose, and lactose. Results: Pediococcus pentosaceus LB44 could demonstrate similar growth and activity at pH 5.0 to 8.0; whereas Weissella confusa LM85 could grow and show activity at pH 5.0 to 10.0, but higher growth was recorded at pH 6.0 to 9.0. The growth and activity of P. pentosaceus LB44 was at 30 to 42°C, whereas W. confusa LM85 was able to grow and demonstrate activity at 30 to 50°C. Both isolates could grow up in 6% NaCl, but growth and activity was higher in the absence of NaCl. The isolates showed optimum growth and activity in the presence of 20 g/L glucose and 40 g/L lactose. In comparison to glucose, the growth and activity were less in the presence of lactose. Conclusions: P. pentosaceus LB44 and W. confusa LM85 could grow and produce bacteriocin under acidic and alkaline conditions at 37°C in the medium without NaCl. These isolates utilized glucose better in comparison with lactose. The optimized conditions are helpful to recover maximum yield of bacteriocin for industrial applications.