Updated Taxonomy of Pectobacterium Genus in the CIRM-CFBP Bacterial Collection: When Newly Described Species Reveal "Old" Endemic Population.

Bacterial collections are invaluable tools for microbiologists. However, their practical use is compromised by imprecise taxonomical assignation of bacterial strains. This is particularly true for soft rotting plant pathogens of the Pectobacterium genus. We analysed the taxonomic status of 265 Pectobacterium strains deposited at CIRM-CFBP collection from 1944 to 2020. This collection gathered Pectobacterium strains isolated in 27 countries from 32 plant species representing 17 botanical families or from nonhost environments. The MLSA approach completed by genomic analysis of 15 strains was performed to update the taxonomic status of these 265 strains. The results showed that the CIRM-CFBP Pectobacterium collection harboured at least one strain of each species, with the exception of P. polonicum. Yet, seven strains could not be assigned to any of the described species and may represent at least two new species. Surprisingly, P. versatile, recently described in 2019, is the most prevalent species among CIRM-CFBP strains. An analysis of P. versatile strains revealed that this species is pandemic and isolated from various host plants and environments. At the opposite, other species gathered strains isolated from only one botanical family or exclusively from a freshwater environment. Our work also revealed new host plants for several Pectobacterium spp.