Isolation and identification of alkaline protease-producing bacterium in the presence of washing-powder from Geinarje hot spring, Ardabil, Iran

Abstract

Proteases are important industrial enzymes used in different areas of industry, mainly detergent, food and leather industries. In this study, novel alkaline protease-producing bacterium was isolated from Geinarje hot spring and examined for maximum protease activity to be utilized in washing-powder. The isolated bacterium was cultured in mineral salt medium including 2% Skim Milk. Proteolytic activity of supernatant was measured by caseinolytic method. The effects of pH, temperature, SDS, Tween 80 and EDTA on protease stability and activity were investigated. The detergent compatibility of protease was assayed. On the basis of phylogenetic analysis and morphological as well as biochemical tests, the isolate was identified as a new strain of Brevibacillus borstelensis capable of generating extracellular alkaline protease. The generated protease was determined as alkaline metallo-protease having high activity at 60 o C and pH 9. Moreover, the alkaline protease was stable in the presence of SDS, Tween 80 and H2O2. It is compatible with commercial detergents. Finding proteases capable of degrading proteins in extreme environment (i.e. alkaline pH, high temperature and presence of surfactants) is valuable in biotechnological and industrial practices. Therefore, it can be utilized in detergent formulation in the future.