A Gram-stain-negative, obligately aerobic bacterium, designated strain B6T, was isolated from rice wine vinegar in the Republic of Korea. Cells were non-motile and oval short rods showing catalase-positive and oxidase-negative activities. Growth was observed at 15-45 °C (optimum, 30 °C) and pH 3.5-8.0 (optimum, pH 5.5-6.5). Strain B6T contained summed feature 8 (comprising C18 : 1ω7c and/or C18 : 1 ω6c), and C16 : 0 as major fatty acids and ubiquinone-9 was identified as the sole isoprenoid quinone. The G+C content of the genomic DNA calculated from the whole genome was 53.1 mol%. Strain B6T was most closely related to Acetobacter pasteurianus LMG 1262T with very high 16S rRNA gene sequence similarity (100 %) and the strains formed a very close phylogenetic lineage together in phylogenetic trees based on 16S rRNA gene sequences. However, relatedness analyses based on concatenated amino acid sequences of 354 core genes and whole-cell MALDI-TOF profiles showed that strain B6T may form a distinct phyletic lineage from Acetobacter species. In addition, average nucleotide identity and in silico DNA-DNA hybridization values between strain B6T and the type strains of Acetobacter species were less than 93.3 and 51.4 %, respectively. The genomic features of strain B6T were also differentiated from those of closely related Acetobacter type strains. Based on the phenotypic, chemotaxonomic and genomic features, strain B6T clearly represents a novel species of the genus Acetobacter, for which the name Acetobacter oryzoeni sp. nov. is proposed. The type strain is B6T (=KACC 21201T=JCM 33371T).
Keywords: Acetobacter oryzoeni; Korean rice wine; new taxa; vinegar.