Scale up of production in a bioreactor of a halotolerant protease from moderately halophilic Bacillus sp. isolated from soil

ABSTRACT

Studies were conducted on the production of protease by moderately halophilic Bacillus sp. on agro-industrial waste materials. The bacterium could efficiently use many agro wastes as substrates but wheat bran supported maximum enzyme production. To ascertain the performance of the process in shake flasks and lab scale bioreactor, experiments were conducted to analyse protease activity utilizing wheat bran as cost effective substrate. The studies unveiled that pH 7.0, temperature 30°C and static conditions were optimal for enzyme production in flask level fermentation. In scale-up fermentation, at optimal pH and temperature, agitation rate of 50 rpm was best for protease production. The enzymatic nature was studied in 10% SDS gels with BSA (2.5 mg/mL) as substrate and banding pattern was compared with undigested BSA as control. The endoprotease nature and the kinetics of protease activity were confirmed. The enzyme retained 37% of its activity even at 5 M NaCl concentration. The proteolytic activity was also confirmed by casein zymogram analysis. The fermentation medium containing inexpensive substrates, physical conditions and ability of Bacillus sp. to exhibit protease activity on a large scale could collectively be useful for commercial production.