State Key Laboratory of Heavy Oil Processing, Key Laboratory of Bioengineering and Biotechnology in Universities of Shandong, Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, China.
Appl Environ Microbiol. 2013 Jan;79(1):121-32. doi: 10.1128/AEM.01889-12. Epub 2012 Oct 12.
The South China Sea (SCS), the largest marginal sea in the Western Pacific Ocean, is a huge oligotrophic water body with very limited influx of nitrogenous nutrients. This suggests that sediment microbial N(2) fixation plays an important role in the production of bioavailable nitrogen. To test the molecular underpinning of this hypothesis, the diversity, abundance, biogeographical distribution, and community structure of the sediment diazotrophic microbiota were investigated at 12 sampling sites, including estuarine, coastal, offshore, deep-sea, and methane hydrate reservoirs or their prospective areas by targeting nifH and some other functional biomarker genes. Diverse and novel nifH sequences were obtained, significantly extending the evolutionary complexity of extant nifH genes. Statistical analyses indicate that sediment in situ temperature is the most significant environmental factor influencing the abundance, community structure, and spatial distribution of the sediment nifH-harboring microbial assemblages in the northern SCS (nSCS). The significantly positive correlation of the sediment pore water NH(4)(+) concentration with the nifH gene abundance suggests that the nSCS sediment nifH-harboring microbiota is active in N(2) fixation and NH(4)(+) production. Several other environmental factors, including sediment pore water PO(4)(3-) concentration, sediment organic carbon, nitrogen and phosphorus levels, etc., are also important in influencing the community structure, spatial distribution, or abundance of the nifH-harboring microbial assemblages. We also confirmed that the nifH genes encoded by archaeal diazotrophs in the ANME-2c subgroup occur exclusively in the deep-sea methane seep areas, providing for the possibility to develop ANME-2c nifH genes as a diagnostic tool for deep-sea methane hydrate reservoir discovery.
南海（SCS）是西太平洋最大的边缘海，是一个巨大的贫营养水体，氮营养物质的流入非常有限。这表明，沉积物微生物固氮在生物可用氮的产生中起着重要作用。为了验证这一假设的分子基础，通过靶向 nifH 和其他一些功能生物标志物基因，在 12 个采样点调查了南海北部（nSCS）包括河口、沿海、近海、深海和甲烷水合物储层或其潜在区域的沉积物固氮微生物菌群的多样性、丰度、生物地理分布和群落结构。获得了多样和新颖的 nifH 序列，显著扩展了现有 nifH 基因的进化复杂性。统计分析表明，沉积物原位温度是影响 nSCS 北部沉积物固氮微生物组合丰度、群落结构和空间分布的最重要环境因素。沉积物孔隙水 NH₄(+)浓度与 nifH 基因丰度呈显著正相关，表明 nSCS 沉积物固氮微生物群在固氮和 NH₄(+)产生过程中是活跃的。其他一些环境因素，包括沉积物孔隙水 PO₄(3-)浓度、沉积物有机碳、氮和磷水平等，也对 nifH 携带微生物组合的群落结构、空间分布或丰度有重要影响。我们还证实，属于 ANME-2c 亚群的古菌固氮菌编码的 nifH 基因仅存在于深海甲烷渗漏区，这为开发 ANME-2c nifH 基因作为深海甲烷水合物储层发现的诊断工具提供了可能性。
