STUDIES ON FERMENTATION OF SYNTHESIZING POLY(HYDROXYBUTYRATE-CO-HYDROXYVALERATE) BY XANTHOBACTER AUTOTROPHICUS
自养黄杆菌合成羟基丁酸和羟基戊酸共聚体的发酵研究

Fermentation test of P( HB-co-HV) was carried out by a Xanthobacter autotrophicus strain which was isolated from soil by our laboratory. The resultes show that the strain is a transport mutant strain for glucose. Glucose, fructose, sucrose, maltose, acetate, propionate, lactate or malate was utilized as sole carbon source, but glucose and fructose were the best among carbon sources. The growth was not affected by (NH4)2SO4 NH4C1 and peptone as different nitrogen sources, but P(HB-co-HV) content of dry cell and the HV/ HB ratio of P(HB-co-HV) were affected. The fed-batch fermentation was carried out for 42h using two-stage cantrolling method. The final cell concentration of 34.9 g . L-1 and the final P(HB-co-HV) concentration of 25.48g . L-1 were obtained in the glucose broth. The cell productivity and P( HB-co-HV) productivity were 0.83g. L-1 .h-1 and 0.61g . L- 1. h-1, respectively. The yield of dry cell to the substrate (Tx/sX the yield of P(HB-co-HV) to the substrate (Yx/s) and the yield of P(HB-co-HV) to the dry cell (Yp/x) were 0.283(g/ g),0.174(g/ g) and 0.730(g / g), respectively. The HB content in the P (HB-co-HV) was adjusted from 24% to 78% by changing the carbon and nitroge component of the medium.