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Some repetitions, omissions or errors have been made in the Validation Lists published in the International Journal of Systematic Bacteriology and they are corrected in this paper.

Gluconacetobacter xylinus (=Acetobacter xylinum) shows variety in acid formation from sugars and sugar-alcohols. Toyosaki et al. proposed new subspecies of G. xylinus (=Acetobacter xylinum) subsp. sucrofermentans in point of acid formation from sucrose and a homology index of 58.2% with the type strain of G. xylinus subsp. xylinus in DNA-DNA hybridization experiments. We tried DNA-DNA hybridization to clarify relationship between acid formation from sugars and classification of G. xylinus. The G + C contents of G. xylinus showed 60.1-62.4 mol% with a range of 2.3 mol%. When type strains of G. xylinus subsp. xylinus, G. xylinus subsp. sucrofermentans, and IFO 3288 forming acid from sucrose, were used as probes, the DNAs from three strains showed 67-100%, 64-89%, and 60-100% similarity to those from sixteen strains including bacteria that form acid from sucrose or not. These results show that homology indexes do not reflect differences of acid formation from sucrose. As a results, the species G. xylinus was proved to be genetically homogeneous.

Thirty-six strains of acetic acid bacteria classified in the genera Acetobacter, Gluconobacter, and Acidomonas were examined for their partial base sequences in positions 1220 through 1375, 156 bases, of 16S rRNA. The strains of the Q10-equipped Gluconobacter species examined were divided into two subgroups, which included the type strains of Gluconobacter oxydans, the type species of the genus Gluconobacter, and of a second species, Gluconobacter cerinus, respectively. The base differences numbered four between the two type strains. The strains of the Q9-equipped species examined classified in the type subgenus Acetobacter of the genus Acetobacter were not very distant phylogenetically from those of the genus Gluconobacter. The calculated number of base differences was 9-6 between the type strains of G. oxydans and G. cerinus and the type strains of Acetobacter aceti and Acetobacter pasteurianus. In contrast, the strains of the Q10-equipped species examined classified in the subgenus Gluconoacetobacter of the genus Acetobacter were very distant phylogenetically from those of the Acetobacter and Gluconobacter species mentioned above. The number of base differences was calculated to be 14-8. Furthermore, the strains of the methanol-assimilating, Q10-equipped species of the genus Acidomonas examined were located in phylogenetically isolated positions. The type strain of Acidomonas methanolica (identical to Acetobacter methanolicus), the type species of the genus Acidomonas, had 16-9 base differences. The data obtained here indicated that the members of the subgenus Gluconoacetobacter of the genus Acetobacter can be distinguished at the generic level. The new genus Gluconoacetobacter was proposed with the type species, Gluconoacetobacter liquefaciens, in recognition of the genus Acidomonas along with the genera Acetobacter and Gluconobacter in the classification of the acetic acid bacteria.