Strains LMG 1627T, LMG 1636T and LMG 1637 were all isolated from cider fermentations in the 1940s and 1950s. A recent study based on MALDI-TOF MS and dnaK gene sequence analyses suggested they represented novel Acetobacter species. In the present study, we determined the whole-genome sequences of these strains and analysed their phenotypic and chemotaxonomic characteristics. A phylogenomic analysis based on 107 single-copy core genes revealed that they represented a single Acetobacter lineage with Acetobacter aceti, Acetobacter sicerae, Acetobacter musti and Acetobacter oeni, Acetobacter estunensis and with Acetobacter nitrogenifigens as an outgroup to this cluster. OrthoANIu value and dDDH analyses among these and other Acetobacter type strains confirmed that these three strains represented two novel Acetobacter species, which could be differentiated from other closely related type strains of Acetobacter by different phenotypic tests, such as ketogenesis from glycerol. We therefore propose to classify strain LMG 1627T in the novel species Acetobacter conturbans sp. nov., with LMG 1627T (=NCIMB 8945T) as the type strain, and to classify strains LMG 1636T and LMG 1637 in the novel species Acetobacter fallax sp. nov., with LMG 1636T (=NCIMB 8956T) as the type strain.
Keywords: Acetobacter; OrthoANIu; acetic acid bacteria; cider fermentation; digital DNA-DNA hybridization.