Zhuhua Chan, Zhaokai Wang,Zhiwei Yi and Runying Zeng
Twenty–six moderately halophilic bacteria were isolated from the sea coast of Sanya city Hainan province China, and screened for their ability to secrete halophilic proteases. Among them, a moderately halophilic strain Pontibacillus sp. SY–8 was investigated for the production of extracellular protease. 16S rRNA gene analysis identified it as Pontibacillus chungwhensis. To enhance protease production, Plackett–Burman (PB) design and response surface methodology (RSM), were used to determine the optimal concentrations. Based on PB design experiments, casein, yeast extract powder, and NaCl were determined as the main factors influencing protease production. The optimal concentration of these components was determined by response surface methodology, which is based on the central composite design. Under the proposed optimized conditions, the protease experimental yield (1441 U ml-1) closely matched the yield predicted by the statistical model (1472.59 U ml-1) with R2 =0.990. An overall 3.56–fold increase in protease production was achieved in the optimized medium as compared with the unoptimized medium.