Metabolic flux analysis of the effect of carbon dioxide top pressure on acetyl coenzyme A and ester production by Saccharomyces cerevisiae

ABSTRACT Carbon dioxide can affect the growth of beer yeast, the production of acetyl-CoA and the synthesis of esters. Through the analysis of metabolic flux, the influence of CO2 top pressure application on the flow direction of carbon metabolism in beer fermentation and the key sites of its action, especially the flow direction of the substrate acetyl-CoA, were studied. It was found that the CO2 top pressure inhibited the formation of acetyl-CoA and higher alcohols but barely affected the activity of alcohol acetyltransferase (AATase). Carbon dioxide top pressure application increased the permeation of acetic acid to extracellular environments, decreased the flux of carbon metabolism toward acetyl-CoA production, and, finally, reduced the synthesis of total esters in beer. Carbon dioxide top pressure application enhanced the pyruvate carboxylation of oxaloacetic acid nodes, while acetyl-CoA, involved in biosynthesis, including that of fatty acids, was inhibited. Graphical abstract