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.