Acetobacter garciniae sp. nov., an acetic acid bacterium isolated from fermented mangosteen peel in Thailand

Two isolates, MS16-SU-2T and MS18- SU- 3, obtained from fermented mangosteen peel in vinegar were suggested to constitute a new species assignable to the genus Acetobacter based on the results of 16S rRNA gene sequencing. The two isolates showed the highest sequence similarity (98.58%) to Acetobacter tropicalis NBRC 16470T and Acetobacter senegalensis LMG 23690T. However, the calculated similarity values were lower than the threshold for species demarcation. The phylogenetic analysis showed that the branches of the two isolates were separated from other Acetobacter species, and the two isolates constituted a new species in the genus Acetobacter. The genomic DNA of isolate MS16- SU- 2T was sequenced. The assembled genome of the isolate was analysed, and the results showed that the highest average nucleotide identity value of 75.9 % was with Acetobacter papayae JCM 25143T and the highest digital DNA-DNA hybridization value of 25.1 % was with Acetobacter fallax LMG 1636T, which were lower than the cutoff values for species delineation. The phylogenetic tree based on the genome sequences showed that the lineage of isolate MS16- SU- 2T was most closely related to A. papayae JCM 25143T and Acetobacter suratthaniensis TBRC 1719T, but separated from the branches of these two species. In addition, the two isolates could be distinguished from the type strains of closely related species by their phenotypic characteristics and MALDI- TOF profiles. Therefore, the two isolates, MS16-SU-2T (=TBRC 12339T=LMG 32243T) and MS18- SU- 3 (=TBRC 12305), can be assigned to an independent species within the genus Acetobacter, and the name of Acetobacter garciniae sp. nov. is proposed for the two isolates.

Automated summary

Two bacterial isolates obtained from fermented mangosteen peel in vinegar were identified as a new species within the genus Acetobacter, named Acetobacter garciniae. The isolates showed high sequence similarity to closely related species based on 16S rRNA gene sequencing, but further genomic and phenotypic analysis revealed distinct characteristics that supported their assignment as a separate species.