Gluconobacter nephelii sp nov., an acetic acid bacterium in the class Alphaproteobacteria

Three strains, RBY-1(T), PHD-1 and PHD-2, were isolated from fruits in Thailand. The strains were Gram-negative, aerobic rods with polar flagella, produced acetic acid from ethanol and did not oxidize acetate or lactate. In phylogenetic trees based on 16S rRNA gene sequences and 16S-23S rRNA gene internal transcribed spacer (ITS) sequences, the strains formed a cluster separate from the type strains of recognized species of the genus Gluconobacter. The calculated 16S rRNA gene sequence and 16S-23S rRNA gene ITS sequence similarities were respectively 97.7-99.7% and 77.3-98.1%. DNA G + C contents ranged from 57.2 to 57.6 mol%. The strains showed high DNA-DNA relatedness of 100% to one another, but low DNA-DNA relatedness of 11-34% to the tested type strains of recognized Gluconobacter species. Q-10 was the major quinone. On the basis of the genotypic and phenotypic data obtained, the three strains clearly represent a novel species, for which the name Gluconobacter nephelii sp. nov. is proposed. The type strain is RBY-1(T) (=BCC 36733(T)=NBRC 106061(T)=PCU 318(T)), whose DNA G + C content is 57.2 mol%.