The genus Gluconacetobacter is divided into two groups phylogenetically, phenotypically and ecologically: the Gluconacetobacter liquefaciens group and the Gluconacetobacter xylinus group. For the latter group, the genus Komagatabacter is newly introduced, and the type species of the new genus is designated as Komagatabacter xylinus (Brown 1886) comb. nov. Twelve species of the Gluconacetobacter xylinus group are transferred to the new genus as new combinations.