Results of H2-consumption experiments during METEOR cruise M64/2@en

The discovery of deep-sea hydrothermal vents in 1977 revolutionized our understanding of the energy sources that fuel primary productivity on Earth. Hydrothermal vent ecosystems are dominated by animals that live in symbiosis with chemosynthetic bacteria. So far, only two energy sources have been shown to power chemosynthetic symbioses: reduced sulphur compounds and methane. Using metagenome sequencing, single-gene fluorescence in situ hybridization, immunohistochemistry, shipboard incubations and in situ mass spectrometry, we show here that the symbionts of the hydrothermal vent mussel Bathymodiolus from the Mid-Atlantic Ridge use hydrogen to power primary production. In addition, we show that the symbionts of Bathymodiolus mussels from Pacific vents have hupL, the key gene for hydrogen oxidation. Furthermore, the symbionts of other vent animals such as the tubeworm Riftia pachyptila and the shrimp Rimicaris exoculata also have hupL. We propose that the ability to use hydrogen as an energy source is widespread in hydrothermal vent symbioses, particularly at sites where hydrogen is abundant.1977年深海热液喷口的发现，彻底革新了人类对地球初级生产力能量来源的认知。热液喷口生态系统以与化能合成细菌建立共生关系的动物为优势类群。迄今为止，仅证实两类能量来源可驱动化能合成共生作用：还原性硫化合物与甲烷。本研究通过宏基因组测序、单基因荧光原位杂交、免疫组织化学、船基培养实验及原位质谱分析，证实大西洋中脊热液喷口的偏顶蛤属（Bathymodiolus）贻贝的共生菌可利用氢气驱动初级生产。此外，太平洋热液喷口的该属贻贝共生菌携带氢氧化过程的关键基因hupL。进一步研究发现，其他热液喷口动物如巨型管蠕虫（Riftia pachyptila）与热液盲虾（Rimicaris exoculata）的共生菌同样携带hupL基因。我们提出，利用氢气作为能量来源的能力在热液喷口共生体系中广泛分布，尤其在氢气富集的生境中更为普遍。