Abstract:Acetic acid is toxic to micro organisms; however, acetic acid bacteria can tolerate high concentrations of acetic acid via a specific mechanism and, therefore, are ideal for use in acetic acid fermentation. In this study, Acetobacter pasteurianus AC2005 was used to evaluate the effect of acetic acid on bacterial growth, glucose metabolism, and intracellular ATP concentration. The results showed that addition of 1% (v/v) acetic acid resulted in an increase in biomass by 92%, glucose consumption per unit mass by 13%, cell metabolic activity by 120%, intracellular ATP concentration by 171%, and pyruvic acid concentration in metabolites by approximately 46%, whereas a decrease in concentration of citric acid and succinic acid in metabolites by 80% and 46%, respectively, as compared to fermentation without addition of acetic acid. Moreover, expression of intracellular proteins, analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) showed that proteins involved in the tricarboxylic acid cycle were up-regulated by addition of acetic acid. Thus, acetic acid bacteria could improve acetic acid tolerance by improving bacterial metabolic activity and increase intracellular ATP concentration.
