Optimization of β-galactosidase production from a native Bacillus spp. isolated from northern soils in Iran

This study aimed to enhance the optimal conditions for the highest production of beta-galactosidase by Bacillus spp. using agro-industries waste under solid state fermentation (SSF). The screening by Taguchi design demonstrated that all of the tested parameters including peanut pod, carbon/nitrogen ratio, incubation time and inducer except the type of solid state had significant (p < 0.05) effect on the beta-galactosidase production. beta-galactosidase assay was done spectrophotometrically using O-nitrophenyl-beta-D-galactopyranoside (ONPG) as the substrate. Maximum beta-galactosidase activity of 2689 U/mg could be obtained at 72 h of fermentation using rice straw. beta-galactosidase activity was observed 1.369 fold with combination of wheat straw and peanut pod instead of wheat straw as solid state substrate for production of enzyme. The optimal ratio of carbon/nitrogen sources for improved beta-galactosidase production was 2% (w/v). The presence of inducer led to significant increase on the enzyme production.