Biochemical Characteristics of Spontaneous Mutants of Acetobacter aceti Deficient in Ethanol Oxidation

It has frequently been observed that acetic acid bacteria showconsiderable genetic instability which causes spontaneous mutations leading to deficiencies in various physiological properties including taxonomically crucial ones.1)2) Amongthese mutants there were strains which had lost their ethanol oxidizing ability.3~5) We isolated a thermophilic strain, No. 1023, of Acetobacter aceti which exhibited elevated resistance to acetic acid which was probably responsible for its thermophilic characteristics.6) Prolonged cultivation of the strain led to the appearance of acetic acid sensitive mutants which were deficient in ethanol oxidizing ability with high frequency.7)