溶氧对Candida glycerinogenes产甘油发酵代谢流分布的影响

分析了耐高渗高产甘油工业菌株产甘油假丝酵母(Candida glycerinogenes)的摇瓶发酵过程，发现溶氧水平是影响C.glycerinogenes 生长、代谢产物生成的重要因素。在此基础上，以5 L发酵罐研究了不同恒溶氧水平甘油的合成过程，通过代谢流分析表明，低溶氧环境下乙醇碳流量增加，导致糖耗快而甘油合成相对较少；碳流分布表明HMP途径在甘油过量合成中起着重要的作用。分析C.glycerinogenes发酵过程中能量代谢和物质代谢（氧化磷酸化和底物水平磷酸化）的变化发现高溶氧环境下ATP合成水平高，一定程度抑制底物水平磷酸化从而使碳流更多地流向了甘油合成；C.glycerinogenes胞内氧化还原平衡(NADH/NAD+比率)的研究进一步解释了产甘油假丝酵母中甘油合成和乙醇生成的竞争关系。

Effect of dissolved oxygen on metabolic flux distribution during glycerol fermentation by Candida glycerinogenes

The glycerol production by fermentation in flasks by Candida glycerinogenes was studied.Dissolved oxygen(DO)was one of the most important factors in the cultivation of the strain by influencing cell growth and metabolites generated.Based on this result,batch fermentation of glycerol under diverse DO levels in a 5 L stirred fermentor was investigated.The metabolic flux analysis explained the phenomenon that sugar consumption was fast and glycerol synthesis was relatively less under low dissolved oxygen levels,mainly due to generated ethanol.Metabolic flux analysis also showed that HMP pathway played an important role in glycerol synthesis.Analysis of carbon metabolization and energy metabolization(oxidative phosphorylation and substrate level phosphorylation)of C.glycerinogenes in the process of glycerol fermentation showed that a high level of ATP synthesis at high dissolved oxygen levels to a certain degree inhibited substrate level phosphorylation so that more carbon flowed to glycerol synthesis.The intracellular redox balance(NADH/NAD+ ratio)reflected the competition between glycerol production and ethanol synthesis.