Reclassification of the strains with low G plus C contents of DNA belonging to the genus Gluconobacter ASAI 1935 (Acetobacteraceae)

Three species, Gluconobacter cerinus, G. asaii, and G. frateurii are report ed to show lower G + C contents than G. oxydans. Isolate 145 also showed a similar G + C content to those of the three species. We try to reclassify t he three species. G. frateurii including a type strain, isolate 145, G. cer inus IFO 3262, 3263, 3269, and G. asaii IFO 3265 formed acid from D-arabito l, ribitol, and L-arabitol. DNAs from G. cerinus IFO 3262, 3263, 3269, and G. asaii IFO 3265 showed 100-53% sequence similarity with that from the typ e strain of G. frateurii, but showed 31-39% and 34-42% similarity with thos e from the type strains of G. cerinus and G. asaii, respectively. On the ba sis of these observations, G. cerinus IFO 3262, 3263, 3269 and G. asaii IFO 3265 were identified as G. frateurii. The type strains of G. cerinus and G . asaii formed acid from D-arabitol, but did not form acid from ribitol and L-arabitol. DNAs from the type strains of G. cerinus and G. asaii showed s pecies-level similarity (95 and 88%) with each other. From these results, w e concluded that G. asaii is conspesific and synonymous with G. cerinus.