Photorhabdus temperata subsp. cinerea subsp. nov., isolated from Heterorhabditis nematodes.

During the characterization of symbiotic bacteria of Hungarian entomopathogenic nematode isolates, a number of bacteria (including strain 3107(T)) isolated from Heterorhabditis downesi and Heterorhabditis megidis showed only moderate 16S rRNA gene sequence similarity to the type strains of all described Photorhabdus species and subspecies. On the basis of the 16S rRNA gene sequence, the phylogenetic relationships of these isolates were uncertain, because of the low bootstrap values. Using gyrB sequences for phylogenetic analysis, these isolates were shown to be part of the species Photorhabdus temperata, with clear separation from both Palaearctic and American strains (phylogenetic distances are 6.9 and 7.9 %, respectively). Physiological properties and carbon-source utilization profiles supported the phylogenetic position of these strains; therefore, a novel subspecies, Photorhabdus temperata subsp. cinerea subsp. nov. is proposed, with the type strain 3107(T) (=DSM 19724(T) =NCAIM B 02271(T)).