Xenorhabdus japonicus sp. nov. associated with the nematode Steinernema kushidai

A new species, Xenorhabdus japonicus, is proposed as the bacterial symbiont of Steinernema kushidai isolated from field soil in Shizuoka Prefecture, Japan. Xenorhabdus japonicus could be distinguished phenotypically and genetically from other Xenorhabdus spp. The type strain of the species, SK-1, a Gram-negative, facultative anaerobe and peritrichously flagellated rod, has colonies with primary and secondary forms. The strain can be differentiated from the type strain of Xenorhabdus nematophilus by several characters, including the formation of arginine dehydrolase, phenylalanine deaminase and lysine decarboxylase, the assimilation of inosine and L-proline and acid production from inositol. The major cellular fatty acids are 16:0, cyclo 17:0 and 18:1. The ubiquinone system is Q-8. The G+C content of DNA is 45.9 mol%. The DNA of strain SK-1 has 20 to 58% homology with that of the type strains of other Xenorhabdus spp.