真氧产碱杆菌利用短链有机酸合成聚羟基烷酸酯

研究了真氧产碱杆菌利用单一以及混合短链有机酸作为碳源进行聚羟基烷酸酯(PHAs)的生物合成. 不同的碳氮浓度比对产物的形成有较大影响；在同样的碳源浓度下，较低氮源浓度更加有利于产物的合成；当短链有机酸浓度为8 g/L、硫酸铵浓度为0.3 g/L时对PHAs的合成最为有利.在4种短链有机酸分别单独用作碳源时，乳酸的消耗速度最快，其次为乙酸、丁酸以及丙酸；在单酸发酵条件下，丁酸的PHAs产量最高(2.72 g/L). 通过比较摇瓶以及5 L罐水平的混合酸发酵发现，发酵罐中的各项发酵指标均优于摇瓶. 研究还发现，真氧产碱杆菌在利用丙酸为碳源进行产物合成时，在发酵后期还伴随有乙酸产生.

Biosynthesis of Polyhydroxyalkanoates by Ralstonia eutropha with Short-chain-length Organic Acids

Biosynthesis of polyhydroxyalkanoates (PHAs) by Ralstonia eutropha with single and mixed short-chain- length organic acids as carbon sources was studied. Different initial concentrations of carbon and nitrogen sources in the media played an important role in the output of PHAs. Under the same concentration of carbon sources, a lower concentration of nitrogen was more propitious to the biosynthesis of PHAs. The concentrations of volatile organic acids at 8 g/L and concentrations of (NH4)2SO4 at 0.3 g/L were probably the most appropriate for the PHAs fermentation. Among the four kinds of short-chain-length organic acids for experiments, lactic acid was used up the first, acetic acid, propionic acid and butyric acid successively. Furthermore, acetic acid was produced when propionic acid was used as carbon source for the biosynthesis of PHAs by Ralstonia eutropha, which was never reported before. Interestingly, when mixed acids were used as carbon sources at the levels of 5 L fermenter and 500 ml flask to biosynthesize PHAs, the 5 L fermenter excelled the latter almost in all technical indexes.