Isolation and Characterization of Komagataeibacter piraceti sp. nov. and Novacetimonas labruscae sp. nov.: Two Novel Microaerobic Cellulose-Producing Acetic Acid Bacteria from Vinegars.

Abstract

The genera Komagataeibacter and Novacetimonas comprise industrially important species that produce various foods, nanocellulose, acetan-like polysaccharides, enantioselective sugars, and other valuable products. Here, we describe two novel strains, Hr1 and Jurk4, isolated from pear and apple-grape organic vinegars that showed very high (≥99.39%) 16S rRNA gene sequence identities to species of the Komagataeibacter and Novacetimonas genera, respectively. However, analysis of the 16S-23S rRNA gene internal transcribed spacer (ITS) sequences revealed only 92.6% sequence identity between the Hr1 strain and its closest relative, Komagataeibacter sucrofermentans LMG 18788^T, and 93.8% sequence identity between the Jurk4 strain and its closest relative, Novacetimonas cocois JCM 31140^T. Further whole-genome analysis showed for both strains an average nucleotide identity (ANI) below 94% and an in silico DNA-DNA hybridization (dDDH) value of less than 70% to their closest species, supporting their distinction as novel species. The strain Hr1 can be phenotypically differentiated from its closest Komagataeibacter species based on its ability to utilize (NH₄)₂SO₄ as the sole nitrogen source in Asai medium with D-glucose and its inability to grow with 1-propanol as a sole carbon source. The strain Jurk4 can be differentiated from other Novacetimonas type strains based on its ability to produce 5-keto-D-gluconic acid, its growth in a medium with glycerol as the sole carbon source, and its inability to grow in an Asai medium with D-glucose. Both strains produce cellulose and possess clusters for acetane-like polysaccharide production, although of different types, which makes them industrially relevant. Based on these findings, we propose Komagataeibacter piraceti sp. nov. Hr1^T (=ZIM B1167^T = LMG 33628^T) and Novacetimonas labruscae sp. nov. Jurk4^T (=ZIM B1166^T = LMG 33630^T) as two novel members of the acetic acid bacteria group.