Abstract

One motile, Gram- negative, non- spore- forming and rod- shaped symbiotic bacterium, strain UCH- 936T, was isolated from Het- erorhabditis atacamensis nematodes. Results of biochemical, physiological, molecular and genomic analyses suggest that it represents a new species, which we propose to name Photorhabdus antumapuensis sp. nov. Digital DNA-DNA hybridization shows that strain UCH- 936T is more closely related to Photorhabdus kleinii DSM 23513T, but shares solely 50.5 % similarity, which is below the 70% cut- off value that delimits species boundaries in bacteria. Phylogenetic reconstructions using whole- genome sequences show that strain UCH- 936T forms a unique clade, suggesting its novel and distinct taxonomic status again. Similarly, comparative genomic analyses shows that the virulence factor flagella- related gene fleR, the type IV pili- related gene pilL and the vibriobactin- related gene vibE are present in the genome of strain UCH- 936T but absent in the genomes of its closest relatives. Biochemically and physiologically, UCH- 936T differs also from all closely related Photorhabdus species. Therefore, Photorhabdus antumapuensis sp. nov. is proposed as a new species with the type strain UCH- 936T (CCCT 21.06T=CCM 9188T=CCOS 1991T).