Screening Of Valienamine-Producing Strain And The Optimization Of Its Fermentation

Validamycins, effective fungicide against the sheath blight of rice plants, is the most widely used homemade farm-antibiotics. It has a low price while valienamine, an important intermediate of medicine, is much more expensive. So it is potential in economical and social benefits to produce valienamine from validamycins.In this dissertation, we were expected to depend on the principium and skill of microorganism culture and enzyme catalyse to research the character of microorganism strain, furthermore, we were also expected to improve valienamine yield via mutation strain and optimizing the whole fermentation process.At first, a highly valienamine-producing variation strain was screened from its original strain by treating with UV as well as NTG., which was fairly different in physiological properties from former. In producing valienamine from validamycins, the new one was double than the old.After the optimizing fermentation process for new strain, the results showed that the optimum temperature was 30℃ ,the optimum pH was 8.0 and the substrate concentration was 1%. Furthermore, the optimum carbon and nitrogen resource were investigated, including inorganic compound which were promoting for fermentation. Validamycins was the optimum corbon resource and the optimum nitrogen resource was sulfate ammonium. Calcium chloride, potassium chloride, bitter salt and zine sulfate could improve the yield of valienamine. The last results showed that under the condition of the best culture medium, the yield of valienmine reached 2.43mg/ml, which compared with the former almost improved 51.9%.At last, the enzyme produced by strain was purified and the character of enzymewas researched. After a series of purification, the multiple of purified enzyme was 15.37 and the production rate was 9.6%, respectively. The analysis of enzymatic character showed that the optimum temperature was 40℃ and the optimum pH was 8.0. The enzyme was relatively stabilization in pH 7-8, and it was thermo-stability below 40℃. Most metal ion such as Ca2+and K+ had forceful activation whereas Fe2+and SDS had distinct restrain. The Michaelis constant (Km) was 22.8mmol/l and Vm was 59.17μgml^-1h^-1.