Microbial Iron Oxidation in the Arctic Tundra and Its Implications for Biogeochemical Cycling
Microbial Iron Oxidation in the Arctic Tundra and Its Implications for Biogeochemical Cycling
复制标题
DOI：
10.1128/aem.02832-15
复制
发表时间：
2015-12-01
影响因子：
4.4
通讯作者：
Bowden, William B.
中科院分区：
文献类型：
--
作者：
Emerson, David;Scott, Jarrod J.;Bowden, William B.
嗜酸性铁氧化细菌在北极苔原中的作用尚不清楚。本研究调查了阿拉斯加北坡图里克湖（纬度68.63，经度-149.60）图里克野外站（TFS）附近的化能合成铁氧化群落。微生物铁垫常见于静止或缓慢流动的水淹没栖息地，其最大的面积范围是在涂层植物茎和沉积物在潮湿的莎草草甸。一些铁氧化细菌（FeOB）产生容易识别的鞘或柄形态型，我们观察到的所有垫中存在和占主导地位。所有地点的冷水温度（9至11摄氏度）和降低的pH值（5.0至6.6）在动力学上有利于微生物铁氧化。基于16 S rRNA基因的五个位点的微生物调查发现变形菌门占优势，β变形菌门和丛枝菌科的成员是最普遍的操作分类单位（OTU）。在相对丰度，分支的石养FeOB组成的5至10%的社区。与蓝藻和叶绿体有关的OTU占群落的3%至25%。氧配置文件显示在一些垫的表面的产氧光合作用的证据，表明光合和FeOB人口的共存。属于推定的铁还原菌（FeRB）的OTU的相对丰度平均约为11%的采样铁垫。垫厌氧孵育与10 mM乙酸盐迅速启动铁还原，表明活跃的铁循环是可能的。冻原上铁席的流行可能会影响碳循环通过岩石自养化学合成，有机碳的厌氧呼吸耦合铁还原，抑制甲烷生成，它可能会影响磷的动态，通过吸附磷的铁氧化物。
The role that neutrophilic iron-oxidizing bacteria play in the Arctic tundra is unknown. This study surveyed chemosynthetic iron-oxidizing communities at the North Slope of Alaska near Toolik Field Station (TFS) at Toolik Lake (lat 68.63, long -149.60). Microbial iron mats were common in submerged habitats with stationary or slowly flowing water, and their greatest areal extent is in coating plant stems and sediments in wet sedge meadows. Some Fe-oxidizing bacteria (FeOB) produce easily recognized sheath or stalk morphotypes that were present and dominant in all the mats we observed. The cool water temperatures (9 to 11 degrees C) and reduced pH (5.0 to 6.6) at all sites kinetically favor microbial iron oxidation. A microbial survey of five sites based on 16S rRNA genes found a predominance of Proteobacteria, with Betaproteobacteria and members of the family Comamonadaceae being the most prevalent operational taxonomic units (OTUs). In relative abundance, clades of lithotrophic FeOB composed 5 to 10% of the communities. OTUs related to cyanobacteria and chloroplasts accounted for 3 to 25% of the communities. Oxygen profiles showed evidence for oxygenic photosynthesis at the surface of some mats, indicating the coexistence of photosynthetic and FeOB populations. The relative abundance of OTUs belonging to putative Fe-reducing bacteria (FeRB) averaged around 11% in the sampled iron mats. Mats incubated anaerobically with 10 mM acetate rapidly initiated Fe reduction, indicating that active iron cycling is likely. The prevalence of iron mats on the tundra might impact the carbon cycle through lithoautotrophic chemosynthesis, anaerobic respiration of organic carbon coupled to iron reduction, and the suppression of methanogenesis, and it potentially influences phosphorus dynamics through the adsorption of phosphorus to iron oxides.