Abstract: The most commonly used microorganism for acetic acid fermentation is Acetobacter pasteurianus. In this investigaton, tricarboxylic acid cycle (TCA cycle) energy metabolism in Acetobacter pasteurianus was interfered by adding acetic acid, TCA cycle inhibitors, and intermediate metabolites. The effects of energy metabolism on the cell growth and acetic acid fermentation of Acetobacter pasteurianus were studied. Results showed that addition of 1% acetic acid obviously strengthened intracellular TCA cycle energy metabolism. The expression levels of the key enzymes involved in the intracellular TCA cycle were significantly up-regulated, and intracellular ATP concentration was increased by 125% compared with that without adding acetic acid. TCA cycle energy metabolism was inhibited by adding TCA cycle inhibitors, the cell growth and acetic acid concentration were significantly inhibited and bacterial biomass was reduced by 90% and 87%, respectively. Acetic acid concentration was reduced by 90% and 94%, respectively. Addition of 0.05% intermediates metabolites (oxaloacetic acid, malic acid, and succinic acid) increased intracellular ATP concentration by 202%, 185% and 165%, respectively, suggesting significantly enhanced TCA cycle-coupled respiratory chain energy metabolism. Bacterial biomass was increased by 92%, 106% and 104% respectively, and acetic acid concentration was increased by 30%, 33% and 31%, respectively, after fermentation for 72 h. Our findings show that TCA cycle energy metabolism has a significant impact on the bacterial growth and acetic acid production of Acetobacter pasteurianus and that strengthening TCA energy metabolism has a positive effect on acetic acid fermentation.

Key words: Acetobacter pasteurianus, tricarboxylic acid cycle, energy metabolism, acetic acid, ATP concentration