| Epothilones are macrolides antibiotics that were candidate drug as inhibitors of the tubulin system as Taxol mimetics. The epothilones, like Taxol and other taxoids, could stabilize microtubules, leading to inhibit the cell cycle and eventually to apoptosis at the concentration of 10-120 ng/ml. The epothilones is regarded as antitumor drugs because of low toxic, water soluble and high activity against cell lines resistant to Taxol. Though the epothilones could be got by chemical synthesis, it is not widely acceptable because of condition, expensive cost, longer synthesis route, lower productivity and environment pollution. The epothilones are usually produced by biosynthesis way while there are many reports on fermentation, however, the low productivity and genetic instability restrain its industrialization. There are two ways to improve the productivity, one is to improve the strain and the other is to optimize the fermentation process.In this study, the analysis and purification ways were optimized. The content of epothilones in the fermentation broth of Sorangium cellulosum was analyzed with HPLC. The factors were optimized with uniform design combined with neural network. Based on the neural network model, the optimal HPLC conditions were obtained genetic algorithm as follow, acetonitrile volume fraction 29.2% , column temperature 34℃and pH of mobile phase 4.23. The effectivity of the epothilone A and B increased significantly after the optimization.The desorption conditions of epothilone were optimized by response surface methodology and the optimal conditions were that the ratio of solvent to broth was 10.5, desorption time was 11.5 hours and desorption was 3 times.Sorangium cellulosum ATCC15384 was mutated by UV, UV-LiCl, DES, UV-HNO2 and protoplast-UV- LiCl. Then , the mutants were screened with medium containing high concentration carbon and nitrogen source, precursor of epothilone or epothilone mimetics. The Sorangium cellulosum UNH127 with high genetic stability was obtained, whose productivity increased 28.2 times as that of the original strain.The medium to culture Sorangium cellulosum UNH127 was optimized with uniform design combined with stepwise regression and the multiple regression model was got. The optimal medium was as follow, KNO3 8, soybean peptide 17.6, beef extract 6.46, yeast extract 1.0, CaCl2 0.25, K2HPO41, NaCl 1 and FeCl3 0.02 (g/L). The predicted max EPOs productivity is 2.48mg/L, and the actual EPOs productivity is 2.36mg/L through validation experiment, which is 7.78 time of that before optimization.The central composite design was employed to optimize the medium containing the precursor of epothilone. The optimal medium is as follow, the sodium propionate concentration 0.48g/L, cysteine concentration 0.06g/L and the opportunity to add cysteine 1.6 h. The predicted optimal productivity is 2.91mg/L, while the actual productivity is 2.88mg/L, which is 22% higher than that without the precursor.The central composite design was employed to optimize the fermentation conditions in flask. The optimal conditions were as follow, temperature 31℃, rotational speed 160 r/min, inculum 9.24%, medium volumn 117ml, pH 6.6, strain age 22.6h and fermentation time 4 days. The predicted optimal productivity of EPOs is 3.22mg/L while the actual productivity is 3.18mg/L, which increase 10%.The anti-tumor activity of Sorangium cellulosum UNH127 fermentation broth was studied. The components of fermentation broth were analyzed by HPLC, and the activity to inhibit the breast cancer cell and hela cell were studied. The linear regression model was got to describe the relationship between components of Sorangium cellulosum UNH127 fermentation broth and anti-tumor activity. The significance was analyzed with t test, which is an important base to screen the active metabolites.
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