A symbiotic bacterium, strain IMI 397775T, was isolated from the insect-pathogenic nematode
Steinernema australe. On the basis of 16S rRNA gene sequence similarity, this bacterial isolate
was shown to belong to the genus Xenorhabdus, in agreement with the genus of its nematode
host. The accurate phylogenetic position of this new isolate was defined using a multigene
approach and showed that isolate IMI 397775T shares a common ancestor with Xenorhabdus
doucetiae FRM16T and Xenorhabdus romanii PR06-AT, the symbiotic bacteria associated with
Steinernema diaprepesi and Steinernema puertoricense, respectively. The nucleotide identity
(less than 97 %) between isolate IMI 397775T, X. doucetiae FRM16T and X. romanii PR06-AT
calculated for the concatenated sequences of five gene fragments encompassing 4275 nt,
several phenotypic traits and the difference between the upper temperatures that limit growth of
these three bacteria allowed genetic and phenotypic differentiation of isolate IMI 397775T from
the two closely related species. Strain IMI 397775T therefore represents a novel species, for
which the name Xenorhabdus magdalenensis sp. nov. is proposed, with the type strain IMI
397775T (5DSM 24915T).