Description of Gluconacetobacter swingsii sp. nov. and Gluconacetobacter rhaeticus sp. nov., isolated from Italian apple fruit.

Two Gram-negative, rod-shaped, non-spore-forming bacteria (DST GL01T and DST GL02T) were isolated from apple fruit juice in the region of the Italian Alps. On the basis of 16S rRNA gene sequence similarities, strains DST GL01T and DST GL02T were shown to belong to the alpha-subclass of the Proteobacteria, and, in particular, to the genus Gluconacetobacter, in the Gluconacetobacter xylinus branch (98.5-100 %). Chemotaxonomic data (major ubiquinone, Q10; predominant fatty acid, C(18 : 1omega7c), accounting for approximately 50 % of the fatty acid content) support the affiliation of both strains to the genus Gluconacetobacter. The results of DNA-DNA hybridizations, together with physiological and biochemical data, allowed genotypic and phenotypic differentiation between strains DST GL01T and DST GL02T and from the 11 validly published Gluconacetobacter species. They therefore represent two new species, for which the names Gluconacetobacter swingsii sp. nov. and Gluconacetobacter rhaeticus sp. nov. are proposed, with the type strains DST GL01T (=LMG 22125T=DSM 16373T) and DST GL02T (=LMG 22126T=DSM 16663T), respectively.