"Candidatus comitans," a bacterium living in coculture with Chondromyces crocatus (myxobacteria)

We describe the phylogenetic position and some taxonomically relevant characteristics of a small pleomorphic gram-negative bacterium that was cocultured with some strains of the myxobacterium Chondromyces crocatus that were isolated from the same geographic and ecological habitat. A 16S ribosomal DNA analysis revealed that the companion was a member of the "Cytophaga-Flavobacterium-Bacteroides" complex and was most closely related to members of the genus Sphingobacterium. The results of a fatty acid analysis, an isoprenoid composition analysis, and a DNA G+C content analysis and the presence of sphingolipids confirmed that this bacterium is affiliated with the genus Sphingobacterium. As the companion bacterium survived for only a few generations on solid media and could not be maintained in pure culture, we assign to this novel taxon that lives in close association with the myxobacterium C. crocatus Candidatus status as "Candidatus comitans."