Close association of active nitrifiers with Beggiatoa mats covering deep-sea hydrothermal sediments.

摘要: Summary Hydrothermal sediments in the Guaymas Basin are covered by microbial mats that dominated nitrate-respiring and sulphide-oxidizing Beggiatoa. The presence of these strongly correlates with sulphide- ammonium-rich fluids venting from subsurface. Because ammonium oxygen form opposed gradients at sediment surface, we hypothesized nitrification is an active process Beggiatoa mats. Using biogeochemical molecular methods, measured determined diversity abundance nitrifiers. Nitrification rates ranged 74 to 605 μmol N l−1 mat day−1, which exceeded those previously hydrothermal plumes other deep-sea habitats. Diversity analyses archaeal bacterial ammonia monooxygenase subunit A genes, 16S ribosomal RNA pyrotags fluorescence situ hybridization confirmed ammonia- nitrite-oxidizing microorganisms were associated Intriguingly, observed cells potential thaumarchaeotal oxidizers attached narrow, Beggiatoa-like filaments. Such a close spatial coupling nitrate respiration large sulphur bacteria novel may facilitate mat-internal cycling nitrogen, thereby reducing loss bioavailable nitrogen sediments.