Distel, D LCavanaugh, Colleen2015-03-311994Distel, D. L., and Colleen M. Cavanaugh. 1994. "Independent phylogenetic origins of methanotrophic and chemoautotrophic bacterial endosymbioses in marine bivalves." Journal of Bacteriology 176, no. 7: 1932-1938.0021-9193http://nrs.harvard.edu/urn-3:HUL.InstRepos:14350510The discovery of bacterium-bivalve symbioses capable of utilizing methane as a carbon and energy source indicates that the endosymbionts of hydrothermal vent and cold seep bivalves are not restricted to sulfur-oxidizing chemoautotrophic bacteria but also include methanotrophic bacteria. The phylogenetic origin of methanotrophic endosymbionts and their relationship to known symbiotic and free-living bacteria, however, have remained unexplored. In situ localization and phylogenetic analysis of a symbiont 16S rRNA gene cloned from the gills of a recently described deep-sea mussel species demonstrate that this symbiont represents a new taxon which is closely related to free-living, cultivable Type I methanotrophic bacteria. This symbiont is distinct from known chemoautotrophic symbionts. Thus, despite compelling similarities between the symbioses, chemoautotrophic and methanotrophic symbionts of marine bivalves have independent phylogenetic origins.en-USJournal Article2015-03-31