Optimization of culture conditions for alkaline protease production from waste breads using Bacillus subtilis

Abstract

An alkaline protease-producing microorganism was isolated from a soil sample which is collected from Cukurova University campus and identified as a strain of Bacillus subtilis. The culture conditions were optimized for maximum enzyme production. Optimum enzyme production was achieved from fermentation medium which includes 1% waste bread and 1% casein powder as carbon and nitrogen source at pH 10.5 and 37 degrees C for 72 h incubation period with agitation of 200 rpm. The optimum inoculum amount and inoculum age were found as 5% and 4 hrs, respectively. Enzyme production reached its maximum value when a baffled Erlenmeyer flask with cotton was used. The approximately 20-fold increase in alkaline protease production was observed as a result of culture medium optimization. Substantial increase in alkaline protease activity was detected in optimized medium (134.64 U/mL) when compared with unoptimized medium (6.45 U/mL). It has been concluded that screening of suitable medium components has asignificant role in the production of alkaline protease by B. subtilis.