Reclassification of Ochrobactrum lupini as a later heterotypic synonym of Ochrobactrum anthropi based on whole-genome...

The genus Ochrobactrum belongs to the family Brucellaceae and its members are known to be adapted to a wide range of ecological niches. Ochrobactrum anthropi ATCC 49188^T and Ochrobactrum lupini LUP21^T are strains isolated from human clinical and plant root nodule samples, respectively, which share high similarity for phylogenetic markers (i.e 100 % for 16S rRNA, 99.9 % for dnaK and 99.35 % for rpoB). In this work, multiple genome average nucleotide identity (ANI) approaches, digital DNA-DNA hybridization (dDDH) and phylogenetic analysis were performed in order to investigate the taxonomic relationship between O. anthropi ATCC 49188^T, O. lupini LUP21^T, and other five type strains from the genus Ochrobactrum. Whole-genome comparisons demonstrated that O. lupini LUP21^T and the Ochrobactrum genus type species, O. anthropi ATCC 49188^T, share 97.55 % of ANIb, 98.25 % of ANIm, 97.99 % of gANI, 97.94 % of OrthoANI and 83.9 % of dDDH, which exceed the species delineation thresholds. These strains are also closely related in phylogenies reconstructed from a concatenation of 1193 sequences from single-copy ortholog genes. A review of their profiles revealed that O. anthropi ATCC 49188^T and O. lupini LUP21^T do not present pronounced differences at phenotypic and chemotaxonomic levels. Considering phylogenetic, genomic, phenotypic and chemotaxonomic data, O. lupini should be considered a later heterotypic synonym of O. anthropi.