Optimization of Chitinase Production by Serratia marcescens with Two-Step Fermentation

Two-step fermentation was used to investigate the fermentation conditions of chitinase production by Serratia marcescens.The optimum bacterial age and the concentrations of carbon source and nitrogen source in the two-step fermentation were obtained through single factor method.At the same time,fermentation time,initial pH value,bacterial dose and loadage were selected as objects with orthogonal design.The chitinase activity reached 17.020 μkat·L-1 under the optimized condition: colloidal chitin 0.8%,yeast extract 1.0%,baceria age 12 h,incubation time 72 h,initial pH 8.5,bacteria dry weight 90 mg,loadage 20 mL in 250 mL conical flask.By adding 0.1% cellulose to two-step fermentation,activity of chitinase was 18.804 μkat·L-1 that was 1.27 times higher than that of one-step fermentation.