有机酸对肺炎克雷伯杆菌厌氧代谢甘油的影响

Effects of Organic Acids Addition on the Anaerobic Fermentation of Glycerol by Klebsiella Pneumoniae

在肺炎克雷伯杆菌厌氧发酵甘油生产1,3-丙二醇的过程中,大量的副产物,特别是乳酸和乙醇等副产物的生成,导致1,3-丙二醇的浓度和得率下降。为了进一步了解有机酸加入后菌体的代谢情况,在菌体生长期同时加入柠檬酸、琥珀酸和延胡索酸三种有机酸的混合液,使其浓度达到3.8 mmol·L-1。5 L罐发酵结果显示,产物的生成发生显著变化。同时,发酵动力学分析表明,有机酸加入后,甘油的比消耗速率和1,3-丙二醇的比生成速率显著提高,而乳酸和乙醇的比生成速率则明显下降。进一步对甘油代谢过程中的碳流分配分析表明,有机酸加入后,甘油进入还原途径的碳流比例由0.45显著增加为0.62,氧化途径的碳流比例由0.53减为0.35。

During the anaerobic fermentation of glycerol to produce 1,3-propanediol by Klebsiella pneumoniae,a lot of by-products（especially lactic acid and ethanol） are formed simultaneously,which lowers the final 1,3-propanediol concentration in the fermentation liquid and the yield of 1,3-propanediol.In order to get the further information of cell metabolism with organic acids addition,the anaerobic fed-back fermentation of glycerol with addition of organic acid mixture（mixture of citrate,succinate and fumarate acids,the concentration of each acid is 3.8 mmol×L-1） in the cell growth period was conducted in a 5 L reactor.The results show that the formation of the products changes significantly when the organic acid mixture was added.At the same time,the kinetic performance analysis of the fermentation indicates that,with the addition of the organic acid mixture,the specific rates of glycerol consumption and 1,3-propanediol formation increase significantly,while the specific formation rates of lactic acid and ethanol decrease sharply.The further analysis of the total carbon flow distribution of glycerol metabolism indicates that,with the addition of the organic acid mixture,the fraction of carbon flowing to the reductive pathway enhances significantly from 0.45 to 0.62,while that to the oxidative pathway decreases from 0.53 to 0.35.