Overproduction of an extracellular protease from Serratia Sp. DT3 just using soybean powder.

摘要

Microbial strain Serratia sp. DT3, isolated from a soil sample in Vietnam, produced an extracellular proteinase with an estimated mol. wt. of 50 kDa. Proteinase production of Serratia sp. DT3 exhibited a parallel profile with cell growth and attained a max. after 28 h of cultivation at 30 degrees C in LB medium. Optimum culture temp. and optimum initial pH for enzyme production were 28 degrees C and 6.0, respectively. Addition of 0.8% (w/v) casein as an inducer to the LB medium increased proteinase production 1.5 fold. Enzyme production was maximal in the culture medium containing 0.5% (w/v) yeast extract or potato as a C source and 1% (w/v) casein as a N source. However, it was found that Serratia sp. DT3 overproduced the extracellular proteinase with a protein level of 1.50 mg/ml supernatant in a simple and low-cost medium containing only 1% (w/v) of soybean powder. Minerals decreased proteinase production slight, or even inhibited it completely in the case of Zn2+ and Fe2+.