Reassessment of the taxonomic position of Rickettsiella grylli.

We determined the 16S rRNA gene sequence of Rickettsiella grylli, an intracellular parasite of Gryllus bimaculatus and related species of crickets. Phylogenetic inferences made from alignment of this sequence with the sequences of other bacteria demonstrated that R. grylli is most closely related to Coxiella burnetii and Legionella species in the gamma subclass of the phylum Proteobacteria. R. grylli was previously thought to be related to members of the order Rickettsiales, but the representatives of this order have been shown to be members of the alpha 1 subclass of the Proteobacteria. Our results indicate that R. grylli should be removed from the order Rickettsiales.