Extraction, purification and characterization of a protease from Micrococcus sp. VKMM 037

Abstract

The haloalkaliphilic bacterium Micrococcus sp. VKMM 037, isolated from an effluent of the caustic soda industry, was found to produce a protease. Maximal proteolytic activity was observed in cell culture grown at 40 °C using 2% (w/v) glycerol, 2% (w/v) beef extract and 2% (w/v) peptone as nutrients in medium also containing 0.85 M NaCl with a pH of 10.0. An efficient purification procedure combining ammonium sulphate precipitation and Q‐Sepharose ion‐exchange chromatography was developed. The purified 41 kDa protease was stable in a temperature range between 20 °C and 60 °C. The protease remained active over a wide range of pH values (4.0–12.0) and NaCl concentrations (0–3.42 M) with an optimum at pH 10.0 and 0.85 M NaCl, respectively. Furthermore, the enzyme remained stable or was only marginally inhibited in the presence of various organic solvents, surfactants and reducing agents. The purified protease of Micrococcus sp. VKMM 037 efficiently removed blood stains within 40 minutes of treatment. Given the biochemical characteristics determined, this novel protease could be exploited as an additive in the detergent industry and also for the synthesis of biomolecules and the degradation of protein.

Keywords:

• haloalkaliphiles
• halotolerant alkaliphilic protease
• Micrococcus sp. VKMM 037

Acknowledgements

This work was supported by a grant from the Government of India Ministry of Science and Technology to the Centre for Advanced studies in Botany, University of Madras, and the Ministry for School and Sports of the Republic of Slovenia research programme P1‐0198. The authors would like to thank Blagajana Herzog‐Velikonja for critical reading of the manuscript.