| Androst-4-ene-3,17-dione(4AD) is the key intermediates of many synthetical steroid drugs,and it is one of the important raw materials for steroid hormones drugs,such as glucocorticoids, sex hormones, anabolic hormone and so on. At present, every countrie in the world has large demand on the steroid drugs. Therefore, 4AD has a very broad market prospects.The fermentation of androst-4-ene-3,17-dione(4AD) by microorganism has such advantages as short cycle of production,stable product,little outgrowth,but the disadvantages of low solubility of the substrate,low transformation rate of 4AD and the product feedback inhibition.By constracting an organic-aqueous two-liquid phase system for fermentations low transformation rate of 4AD and the product feedback inhibition were solved. After that ,the effect of the main factors in the medium on fermentation results were study,and a kind of quick and effevtive mensurating method was established. At last,the best fermentation condition in 5L bio-reator was gained.The main results were as following:1. When the organic phase and its proportion were soybean oil and 22%,and the concentration of the substrate was 4g/L,the fermentation results was the best: the concentration of the substrate was improved for 3 times,and the transformation rate of 4AD was increased from 15.1% to 85.7%.2.When the main factors in the medium were :rice steep liquor 70g/L, carbamide 2.00g/L, Fe2+ 0.05g/L, Mg2+ 0.06g/L ,Ca2+ 0.100g/L, the transformation rate of 4AD was most achieved 86.8%.3.Comparing the mensurating results of TLC, UV, HPLC, GC,a kind of mensurating method ,which was combinative TLC with GC,was established for the transformation of phytosterol into 4AD.4.The best fermentation condition in 5L bio-reactor were stir speed 600r/min, venting speed 3.00L/min, inoculation volumeon 12%, medium volume 3L, pH 8.0, temperature 30°C.At this time, the concentration of 4AD in yeast water was the most ,to be achieved 2.42g/L,and the transformation rate of 4AD was 92.1%.
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