The evolutionary response of alcohol dehydrogenase and aldehyde dehydrogenases of Acetobacter pasteurianus CGMCC 3089 to ethanol adaptation

The acetic acid bacterium Acetobacter pasteurianus is used for vinegar fermentation with ethanol as a substrate. However, growth of A. pasteurianus is inhibited by high ethanol concentrations. The ethanol resistance of A. pasteurianus CGMCC 3089 was improved using a continuous ethanol stress adaptation culture. Characterization studies of strains during evolutionary processes were performed for improved ethanol resistance by comparison of cell growth and alcohol dehydrogenase (ADH) and aldehyde dehydrogenases (ALDH) activities. Improved resistance against ethanol was an inheritable phenotype instead of a transient physiologic adaptation. The evolutionary response of ADH and ALDH to high concentrations of ethanol was responsible for the ethanol resistance of A. pasteurianus, instead of mutations in the open reading frames of ADH and ALDH, or long nucleotide sequence insertion or deletion in the genome.