Optimization of culture conditions for the production of halothermophilic protease from halophilic bacterium Chromohalobacter sp. TVSP101

摘要

An extremely halophilic Chromohalobacter sp. TVSP101 was isolated from solar salterns and screened for the production of extracellular halothermophilic protease. Identification of the bacterium was done based upon biochemical tests and the 16S rRNA sequence. The partially purified enzyme displayed maximum activity at pH 8 and required 4.5 M of NaCl for optimum proteolytic activity. In addition, this enzyme was thermophilic and active in broad range of temperature 60–80°C with 80°C as optimum. The Chromohalobacter sp. required 4 M NaCl for its optimum growth and protease secretion and no growth was observed below 1 M of NaCl. The initial pH of the medium for growth and enzyme production was in the range 7.0–8.0 with optimum at pH 7.2. Various cations at 1 mM concentration in the growth medium had no significant effect in enhancing the growth and enzyme production but 0.5 M MgCl2 concentration enhanced enzyme production. Casein or skim milk powder 1% (w/v) along with 1% peptone proved to be the best nitrogen sources for maximum biomass and enzyme production. The carbon sources glucose and glycerol repressed the protease secretion. Immobilization of whole cells in absence of NaCl proved to be useful for continuous production of halophilic protease.