Response of surface optimization for the enhanced production of alkaline protease isolated from Bacillus sp. with bean husk as a new substrate

Document Type : Research Article


1 Department of Microbiology, Faculty of Sciences, Islamic Azad University, Rasht Branch, P.O. Box 41335-3516, Rasht, Iran

2 Department of Microbiology, Sciences and research branch, Islamic Azad University, Rasht Iran


Optimization of the fermentation medium for maximum alkaline protease production was carried out. Fifteen positive isolates were examined for their extent of alkaline protease production. The most potent producer was identified as Bacillus sp. The solid substrate screening showed that the combination of wheat straw and bean husk was the best one. The initial screening by using Plackett–Burman’s design demonstrated that among the tested factors, casein, ammonium sulphate and pepton as the nitrogen sources and glucose, lactose and sucrose as carbon sources, glucose and casein significantly (P < 0.05) enhanced the protease production in combinatory solid state fermentation (SSF). Further optimization of protease production by Bacillus sp. strain k7 on different factors such as incubation time (84 h), inoculums size (64%), initial moisture content (97%), buffer volume (4.9%) in SSF by applying RSM was achieved.