Résumé
Aeromonas media groups bacteria mainly found in aquatic habitats that can act occasionally as opportunistic pathogens in human and animals. The aim of this study is to explore the diversity of the bacteria currently affiliated to the species A. media. Forty strains were included in a population study integrating, multilocus genetics, genomics, phylogenetics as well as lifestyle and evolutionary features. Sixteen gene-based multilocus phylogeny delineated three clades. The emergence of clades was mainly due to mutations even if horizontal gene transfers occurred within and between clades. Data from 14 whole genome sequences showed that clades corresponded to different groups defined by both average nucleotide identity and in silico DNA-DNA Hybridization, i.e. to different genomospecies. DL-lactate utilization, cefoxitin susceptibility and several signatures clearly distinguished two clades/genomospecies, which were proposed as two species: emended A. media and Aeromonas alphaquinta sp. nov. (type strain LMG 13459T = ATCC 51107T = CIP 74.32T). The third clade was proposed as Aeromonas sp. genomospecies Paramedia (reference strain 1086C = CECT 8838 = LMG 28708) awaiting larger number of strains for a robust species description. Data used for polyphasic barcoding that support the description A. alphaquinta sp. nov. and the emendation A. media were further analyzed in an integrative approach giving a more comprehensive knowledge of the two species among aeromonads.