Sodalis praecaptivus subsp. spalangiae subsp. nov., a nascent bacterial endosymbiont isolated from the parasitoid wasp, Spalangia cameroni

Abstract

An endosymbiotic bacterium of the genus Sodalis, designated as strain HZT, was cultured from the parasitoid wasp Spalangia cameroni, which develops on the pupae of various host flies. The bacterium was detected in S. cameroni developed on houseflies, Musca domestica, in a poultry facility in Hazon, northern Israel. After culturing, this bacterium displayed no surface motility on Luria–Bertani agar and was rod-shaped and irregular in size, ~10–30 nm in diameter and 5–20 µm in length. Phylogenetic analyses revealed that strain HZT is closely related to Sodalis praecaptivus strain HST, a free-living species of the genus Sodalis that includes many insect endosymbionts. Although these bacteria maintain >98% sequence identity in shared genes, genomic characterization revealed that strain HZT has undergone substantial reductive evolution, such that it lacks many gene functions that are maintained in S. praecaptivus strain HST. Based on the results of phylogenetic, genomic and chemotaxonomic analyses, we propose that this endosymbiont should be classified in a new subspecies as S. praecaptivus subsp. spalangiae subsp. nov. The type strain for this new subspecies is HZT (=ATCC TSD-398T=NCIMB 15482T). The subspecies Sodalis praecaptivus subsp. praecaptivus strain HST is created automatically with the type strain ATCC BAA-2554T (=DSMZ 27494T).