Abstract
In this study a novel thermo stable alkaline protease producing Streptomyces sp. Al-Dhabi-82 was isolated from the soil. The effect of fermentation period on enzyme production by Streptomyces sp. Al-Dhabi-82 was optimized in submerged fermentation. Protease activity was found to be maximum after 5 days of incubation (129.5 +/- 7.1 U/ml) and depleted after 6 days of incubation (113.8 +/- 4.1 U/ml). Enzyme production increases with the increase in pH up to 9.0 (136.2 +/- 3.6 U/ml) and enzyme production depleted significantly at pH 11.0 (67 +/- 2.9 U/ml). Maximum production of protease was observed at 40 degrees C (164 +/- 11.1 U/ml). Among the evaluated carbon sources, maltose significantly influenced on protease production (212 +/- 14.8 U/ml). The optimum amount of protease (269 +/- 10.4 U/ml) produced by Streptomyces sp. Al-Dhabi-82 was observed in the production medium containing yeast extract. Enzyme production was maximum in the presence of 0.15% Ca2+. The specific activity of crude enzyme was 26 U/ mg protein and it increased as 276 U/mg protein after chromatography separation. The molecular weight of purified protease obtained from sephadex G-75 gel filtration chromatography was estimated to be 37 kDa using SDS-PAGE. This enzyme showed high activity at pH 9.0, and lost about 16% activity at pH 10. The optimum temperature for Streptomyces sp. Al-Dhabi-82 protease was 40 degrees C. The extracellular alkaline protease from Streptomyces sp. Al-Dhabi-82 hydrolyzed chicken feather completely. (C) 2019 The Authors. Published by Elsevier B.V. on behalf of King Saud University.