Abstract: Pseudomonas sp. TS1138 was used as the test strain to produce L-cysteine. The culture medium components and enzyme production conditions of strain Pseudomonas sp. TS1138 were optimized by response surface methodology. Initially, Plackett-Burman design was used to evaluate the process variables which were relevant to the enzyme production. Four statistically significant parameters including DL-ATC, corn liquid, speed of revolution and liquid volume were selected and utilized in order to optimize the process. The optimized levels of these factors were defined by response surface analysis (RSA). The optimized medium and conditions of producing enzyme were as follows: 30 g/L glucose, 3.0 g/L DL-ATC·3H2O, 3.1 ml/L corn steep liquor, 3 g/L urea, 1 g/L MnSO·4H2O, 3 g/L K2HPO4·3H2O, 0.01 g/L FeSO4·7H2O, 0.5 g/L MgSO·4 7H2O, 3 g/L NaCl, 190 r/min, 42 ml/500 ml, 10% of inoculum size, initial pH7.5 and 29 ℃. Cell enzyme activity was 2255 U/ml under the optimum conditions, improved by 9.8% compared with 2053 U/ml under the original conditions.

Key words:  , L-cysteine； enzymatic synthesis； response surface methodology； Pseudomonas sp.；