DeChaine Eric G, Cavanaugh Colleen M
Department of Organismic and Evolutionary Biology, Havard University, The Biological Laboratories, 16 Divinity Avenue, Cambridge, MA 02138, USA.
Prog Mol Subcell Biol. 2006;41:227-49. doi: 10.1007/3-540-28221-1_11.
The symbioses between invertebrates and chemosynthetic bacteria allow both host and symbiont to colonize and thrive in otherwise inhospitable deep-sea habitats. Given the global distribution of the bathymodioline symbioses, this association is an excellent model for evaluating co-speciation and evolution of symbioses. Thus far, the methanotroph and chemoautotroph endosymbionts of mussels are tightly clustered within two independent clades of gamma Proteobacteria, respectively. Further physiological and genomic studies will elucidate the ecological and evolutionary roles that these bacterial clades play in the symbiosis and chemosynthetic community. Due to the overall abundance of the methanotrophic symbioses at hydrothermal vents and hydrocarbon seeps, they likely play a significant, but as of yet unquantified, role in the biogeochemical cycling of methane. With this in mind, the search for methanotrophic symbioses should not be restricted to these known deep-sea habitats, but rather should be expanded to include methane-rich coastal marine and freshwater environments inhabited by methanotrophs and bivalves. Our current understanding of the bathymodioline symbioses provides a strong foundation for future explorations into the origin, ecology, and evolution of methanotroph symbioses, which are now becoming possible through a combination of classical and advanced molecular techniques.
无脊椎动物与化学合成细菌之间的共生关系使宿主和共生体能够在原本不适宜居住的深海栖息地定殖并茁壮成长。鉴于深海贻贝共生关系的全球分布，这种关联是评估共生关系的共同物种形成和进化的绝佳模型。到目前为止，贻贝的甲烷营养型和化学自养型内共生体分别紧密聚集在γ-变形菌的两个独立分支中。进一步的生理学和基因组学研究将阐明这些细菌分支在共生关系和化学合成群落中所起的生态和进化作用。由于热液喷口和烃类渗漏处甲烷营养型共生关系的总体丰富性，它们可能在甲烷的生物地球化学循环中发挥重要作用，但目前尚未量化。考虑到这一点，对甲烷营养型共生关系的探索不应局限于这些已知的深海栖息地，而应扩大到包括富含甲烷的沿海海洋和淡水环境，这些环境中有甲烷营养型生物和双壳类动物栖息。我们目前对深海贻贝共生关系的理解为未来探索甲烷营养型共生关系的起源、生态和进化提供了坚实的基础，通过经典和先进分子技术的结合，现在对甲烷营养型共生关系的探索已成为可能。
