Transgalactosylating β-galactosidase from probiotic Lactobacillus plantarum MCC2156: production and permeabilization for use as whole cell biocatalyst.

Key nutritional factors were optimized for the maximum production of transgalactosylating β-galactosidase from Lactobacillus plantarum MCC2156. Galactose, yeast extract, sodium acetate and manganese sulphate were the most important nutrients affecting β-galactosidase production. Maximum β-galactosidase production (3015 miller units) was obtained by culturing L. plantarum in the optimized fermentation medium containing (w/v) galactose (4 %), yeast extract (2 %), sodium acetate (3 %) and manganese sulphate (0.075 %) with an optimum medium pH of 7.0, after 14 h of incubation at 35 °C. Further, permeabilization of L. plantarum cells using various chemical/ solvents for maximum β-galactosidase activity was performed for use as whole cell biocatalyst. Mixture of ethanol: n-butanol was found to effectively permeabilize the cells with maximum β-galactosidase activity under the following optimum conditions; 1: 1 mixture of ethanol (10 %, v/v): n-butanol (30 %, v/v) with a contact time of 10 min at 28 ± 2 °C.