Acetobacter sacchari sp. nov., for a plant growth-promoting acetic acid bacterium isolated in Vietnam

Purpose Two bacterial strains, designated as isolates VTH-Ai14 T and VTH-Ai15, that have plant growth-promoting ability were isolated during the study on acetic acid bacteria diversity in Vietnam. The phylogenetic analysis based on 16S rRNA gene sequences showed that the two isolates were located closely to Acetobacter nitrogenifigens RG1 T but formed an independent cluster. Methods The phylogenetic analysis based on 16S rRNA gene and three housekeeping genes’ ( dna K, gro EL, and rpo B) sequences were analyzed. The genomic DNA of the two isolates, VTH-Ai14 T and VTH-Ai15, Acetobacter nitrogenifigens RG1 T , the closest phylogenetic species, and Acetobacter aceti NBRC 14818 T were hybridized and calculated the %similarity. Then, phenotypic and chemotaxonomic characteristics were determined for species’ description using the conventional method. Results The 16S rRNA gene and concatenated of the three housekeeping genes phylogenetic analysis suggests that the two isolates were constituted in a species separated from Acetobacter nitrogenifigens, Acetobacter aceti , and Acetobacter sicerae . The two isolates VTH-Ai14 T and VTH-Ai15 showed 99.65% and 98.65% similarity of 16S rRNA gene when compared with Acetobacter nitrogenifigens and Acetobacter aceti and they were so different from Acetobacter nitrogenifigens RG1 T with 56.99 ± 3.6 and 68.15 ± 1.8% in DNA-DNA hybridization, when isolates VTH-Ai14 T and VTH-Ai15 were respectively labeled. Moreover, the two isolates were phenotypically distinguished from Acetobacter nitrogenifigens in growth in the presence of 0.35% acetic acid ( v / v ), on nitrogen-free LGI medium and D-mannitol, and in no ability to solubilize phosphate. Conclusion Therefore, the two isolates, VTH-Ai14 T (= VTCC 910031 T = BCC 67843 T = TBRC 11175 T = NRIC 0977 T ) and VTH-Ai15 (= VTCC 910032 = BCC 67844 = TBRC 11176 = NRIC 0978), can be assigned to an independent species within the genus Acetobacter , and the name of Acetobacter sacchari sp. nov. is proposed for the two isolates.