A novel species of Xenorhabdus indica sp. nov., symbiotically associated with entamopathogenic nematode Steinernema thermophilum

Abstract

In the search for novel Xenorhabdus strains in a recently described nematode species, Steinernema thermophilum, three strains (strain 28T=DSM 17382T, strain 42=DSM 17383 and strain 43=DSM 17384) were isolated from three independent isolation approaches from crushed mixture of infective juveniles. 16S rRNA gene sequence comparison of strains 28T and DSM 17383 indicated identity and the phylogenetic position pointed towards an individual taxon within the phylogenetic dendrogram of Xenorhabdus type strains. The nearest phylogenetic relatives of strain 28T were Xenorhabdus poinarii and Xenorhabdus szentirmaii (97.7% each). The three isolates were almost identical in reaction towards the API and BIOLOG substrate panels but differed in their reactions from those of the established type strains of the genus Xenorhabdus. These clear genomic and metabolic differences let us propose a new species, Xenorhabdus indica sp. nov. for the three clones. The type strain is strain 28T, DSM 17382T, CIP 108830T.