Study And Optimization Of The Industrial Cultivation Conditions Of S11 Enzymatic Germ

L-cysteine is an elementary S-containing amino acid, which has been found utility as medicine, raw materials for medicine, food additive, additive for cosmetics and fodder. In our lab, a germ 11 that can convert DL-ATC to L-cysteine was selected from the soil containing high concentration DL-ATC. Analyzed the phenotypic, physiological and morphological information to identify the taxonomy status of the germ 11 by using polyphasic taxonomy, the germ 11 probably was a subspecies of micrococcus, which can use DL-ATC as substrate to synthesize L-cysteine.The identification of germ, verification of products, conditions of growth and enzyme producing were studied in detail. The results were as follow.The qualitative and quantitative detecting method of L-cysteine(the paper developing color method and the DTNB) and enzyme activity are established. Conditions of growth and enzyme producing were studied in detail.Through investigating of the growth condition we found that glucose is the most suitable carbon source of growth and urea is most optimum nitrogen source. Two level factorials designs of Placket-Burman were constructed to select culture medium components of 11. Three important components, which were glucose, urea and rotate speed were screened. The optimized level of these factors was determined by response surface analysis. The shake flask cultivations showed the cell concentration increased 16.9% at optimized condition.We also found three important components of the enzymatic production seed, which were glucose, DL-ATC and rotate speed. The shake flask cultivations showed that and enzyme activity increased 7.8% at optimized condition. The optimized enzyme yield conditions were: initial pH 7.0-7.5, 30℃.