Nineteen thermophilic bacterial isolates were screened and only two (PW10 and PS7) produced extracellular, auto inducible β-galactosidase. PW10 and PS7 was Gram’s positive, rod shaped and exhibit growth between 50-80 °C and pH 5-9. Optimum βgalactosidase activity of U/mg/min was observed at 60 °C and pH 7 for PS7, while U/mg/min at 60 °C and pH 9 for PW10. 16S rDNA sequencing of PW10 showed 99% similarity with Anoxybacillus flavithermus and PS7 with Bacillus licheniformis (GenBank accession no. KF039883 and KF039882). Lactose supplementation enhanced β-galactosidase production by folds in PS7, while folds in PW10. Ethanol and hydrogen peroxide does not affect growth of PS7 isolate, while ethanol decreased the growth by folds. Hydrogen peroxide inhibited growth of PW10. β-galactosidase of PS7 was metal independent, while β-galactosidase was metal activated in PS10. Presence of lactose and glucose activated β-galactosidase, while glucose did not affect -galactosidase activity in both isolates. Maximum β-galactosidase production was observed at ~ 72 h of incubation. Km value of mM with ONPG (60° C) was determined for PS7 and mM for PW10. β-galactosidase of both isolates was stable at 4 and 25 °C for 5-6 days. | Characterization of thermally stable β galactosidase from Anoxybacillus Flavithermus and Bacillus Licheniformis isolated from Tattapani hotspring of north western Himalayas, India
