Effect of different dissolved oxygen concentrations on metabolism in Corynebacterium glutamicum

Abstract:

[Objective] We cultivated Corynebacterium glutamicum under 0, 30 and 50% dissolved oxygen (DO) to study the change of metabolism. [Methods] The change of substance metabolism was studied by detecting the content of organic acids and amino acids, the activity of key enzymes and expression of their coding genes under different DO level. Meanwhile, the effect of different DO level on energy metabolism was analyzed by detecting the content of cellular reducing power and ATP. [Results] DO level affected metabolism in C. glutamicum and the content of organic acids and amino acids was also changed. Especially under low DO level, cellular oxidative phosphorylation was weakened, resulting in the decrease of ATP provided for life activity. Therefore, the excessive substrate-level phosphorylation was needed to generate ATP for meeting the demand of life activity. In this case, the accumulation of cellular NADH increased; the flow of TCA cycle decreased and switched to the glycolysis pathway and glyoxylate cycle. As a result, a variety of organic acids and amino acids was generated, including lactate, valine and leucine and so on, which can further influence the production of target product under zero dissolved oxygen concentration. [Conclusion] The results are of certain guiding significance for taking further measures to optimize the control strategy of dissolved oxygen and improve product yield in fermentation of Corynebacterium glutamicum.

Key words:Corynebacterium glutamicum, Dissolved oxygen, Metabolites, Enzyme activities, Key genes