In contrast to many other marine invertebrates that generally harbor only a single bacterial symbiont, gutless oligochaetes are unique in having established highly specific and stable associations with multiple endosymbiotic species. These small worms have completely reduced their digestive and excretory systems and live in obligate symbiosis with phylogenetically diverse co-occurring bacterial symbionts. This project will address the diversity and functional roles of symbiotic bacteria in the gutless marine oligochaete Olavius algarvensis through comparative metagenomics. These worms harbor a microbial community of five co-occurring symbionts with very different metabolic pathways and evolutionary origins. In addition to the interactions of the symbionts with their hosts, these associations are unique in that at least some of the oligochaete symbionts also share a mutualistic relationship with each other. Thus, these symbioses offer the rare opportunity to not only identify the genomic differences and similarities that contribute to the diverse interactions between bacteria and their eukaryotic hosts, but also to examine the metabolic and genetic interactions within the symbiotic bacterial consortium.
CSP project participants: Nicole Dubilier (proposer), Frank Oliver Glöckner, and Rudolf I. Amann (Max Planck Inst. for Marine Microbiology).