Reclassification of genus Izhakiella into the family Erwiniaceae based on phylogenetic and genomic analyses

Abstract

The genus Izhakiella was established and designated as a member of the family Enterobacteriaceae in 2016. Although the taxonomical classification of most members in this family has been relatively resolved after two reclassifications in 2016 and 2017, the classification of the genus Izhakiella remains ambiguous. In this study, a polyphasic approach was used to provide evidence supporting the fact that the genus Izhakiella should no longer be considered a member of Enterobacteriaceae and proposes its reclassification into the family Erwiniaceae. The phylogenetic tree of type species in the families Enterobacteriaceae and Erwiniaceae based on the sequences of the 16S rRNA gene, rpoB housekeeping gene, and the whole-genome comprising the 92 core genes revealed that the genus Izhakiella forms a phylogenetic lineage within the family Erwiniaceae. The average nucleotide identity (ANI) value of the type species with genus Izhakiella was found to be higher for the family Erwiniaceae than that for the family Enterobacteriaceae. Notably, 12 conserved signature indels (CSIs) that are exclusively shared among the Erwiniaceae clade members were found in the type strains of the genus Izhakiella. Based on these analyses, this study suggests the reclassification of I. capsodis and I. australiensis into the family Erwiniaceae.