Loss of acetic acid resistance and ethanol oxidizing ability in an Acetobacter strain.

Abstract

A thermophilic strain, No. 1023, of Acetobacter aceti was isolated, by which it became possible to carry out submerged vinegar production at 35°C. The thermophilic property of the strain correlated closely with its acetic acid resistance. Strain No. 1023 lost acetic acid resistance at high frequency (more than 55% in isolated strains) and lost ethanol oxidizing ability at lower frequency (about 40%) compared to the above in the stationary growth phase in a liquid medium containing ethanol. The loss of these properties during the stationary phase was confirmed using a genetically marked strain (pro−) of No. 1023. Such frequent loss of acetic acid resistance and ethanol oxidizing ability suggested a relationship between these properties and a plasmid. A plasmid, pTA 5001, was found in strain No. 1023, and its molecular weight was determined to be 17 × 106 daltons by electron microscopy. The plasmid, however, seemed to have no direct connection with acetic acid resistance or ethanol oxidizing ability, becaus...