Winkel Matthias, de Beer Dirk, Lavik Gaute, Peplies Jörg, Mußmann Marc
Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, 28359, Bremen, Germany.
Environ Microbiol. 2014 Jun;16(6):1612-26. doi: 10.1111/1462-2920.12316. Epub 2013 Nov 28.
Hydrothermal sediments in the Guaymas Basin are covered by microbial mats that are dominated by nitrate-respiring and sulphide-oxidizing Beggiatoa. The presence of these mats strongly correlates with sulphide- and ammonium-rich fluids venting from the subsurface. Because ammonium and oxygen form opposed gradients at the sediment surface, we hypothesized that nitrification is an active process in these Beggiatoa mats. Using biogeochemical and molecular methods, we measured nitrification and determined the diversity and abundance of nitrifiers. Nitrification rates ranged from 74 to 605 μmol N l(-1) mat day(-1), which exceeded those previously measured in hydrothermal plumes and other deep-sea habitats. Diversity and abundance analyses of archaeal and bacterial ammonia monooxygenase subunit A genes, archaeal 16S ribosomal RNA pyrotags and fluorescence in situ hybridization confirmed that ammonia- and nitrite-oxidizing microorganisms were associated with Beggiatoa mats. Intriguingly, we observed cells of bacterial and potential thaumarchaeotal ammonia oxidizers attached to narrow, Beggiatoa-like filaments. Such a close spatial coupling of nitrification and nitrate respiration in mats of large sulphur bacteria is novel and may facilitate mat-internal cycling of nitrogen, thereby reducing loss of bioavailable nitrogen in deep-sea sediments.
瓜伊马斯盆地的热液沉积物被微生物席覆盖，这些微生物席以进行硝酸盐呼吸和硫化物氧化的贝氏硫菌为主。这些微生物席的存在与从地下涌出的富含硫化物和铵的流体密切相关。由于铵和氧气在沉积物表面形成相反的梯度，我们推测硝化作用在这些贝氏硫菌席中是一个活跃的过程。我们使用生物地球化学和分子方法测量了硝化作用，并确定了硝化细菌的多样性和丰度。硝化速率范围为74至605μmol N l⁻¹ 席⁻¹ 天⁻¹，超过了之前在热液羽流和其他深海栖息地测得的速率。对古菌和细菌氨单加氧酶亚基A基因、古菌16S核糖体RNA焦磷酸测序标签以及荧光原位杂交的多样性和丰度分析证实，氨氧化和亚硝酸盐氧化微生物与贝氏硫菌席有关。有趣的是，我们观察到细菌和潜在的奇古菌门氨氧化菌的细胞附着在狭窄的、类似贝氏硫菌的丝状体上。在大型硫细菌席中硝化作用和硝酸盐呼吸如此紧密的空间耦合是新颖的，可能有助于席内氮的循环，从而减少深海沉积物中生物可利用氮的损失。
