Angell John H, Peng Xuefeng, Ji Qixing, Craick Ian, Jayakumar Amal, Kearns Patrick J, Ward Bess B, Bowen Jennifer L
Biology Department, University of Massachusetts Boston, Boston, MA, United States.
Department of Geosciences, Princeton University, Princeton, NJ, United States.
Front Microbiol. 2018 Feb 12;9:170. doi: 10.3389/fmicb.2018.00170. eCollection 2018.
Salt marshes provide many key ecosystem services that have tremendous ecological and economic value. One critical service is the removal of fixed nitrogen from coastal waters, which limits the negative effects of eutrophication resulting from increased nutrient supply. Nutrient enrichment of salt marsh sediments results in higher rates of nitrogen cycling and, commonly, a concurrent increase in the flux of nitrous oxide, an important greenhouse gas. Little is known, however, regarding controls on the microbial communities that contribute to nitrous oxide fluxes in marsh sediments. To address this disconnect, we generated profiles of microbial communities and communities of micro-organisms containing specific nitrogen cycling genes that encode several enzymes ( related to nitrous oxide flux from salt marsh sediments. We hypothesized that communities of microbes responsible for nitrogen transformations will be structured by nitrogen availability. Taxa that respond positively to high nitrogen inputs may be responsible for the elevated rates of nitrogen cycling processes measured in fertilized sediments. Our data show that, with the exception of ammonia-oxidizing archaea, the community composition of organisms involved in the production and consumption of nitrous oxide was altered under nutrient enrichment. These results suggest that previously measured rates of nitrous oxide production and consumption are likely the result of changes in community structure, not simply changes in microbial activity.
盐沼提供了许多具有巨大生态和经济价值的关键生态系统服务。一项关键服务是从沿海水域去除固定氮，这限制了因营养物质供应增加而导致的富营养化的负面影响。盐沼沉积物的营养物质富集导致更高的氮循环速率，并且通常会同时增加一氧化二氮（一种重要的温室气体）的通量。然而，对于导致盐沼沉积物中一氧化二氮通量的微生物群落的控制因素知之甚少。为了解决这一脱节问题，我们绘制了微生物群落以及含有特定氮循环基因的微生物群落图谱，这些基因编码几种与盐沼沉积物中一氧化二氮通量相关的酶。我们假设负责氮转化的微生物群落将由氮的可用性构成。对高氮输入有积极反应的分类群可能是导致在施肥沉积物中测得的氮循环过程速率升高的原因。我们的数据表明，除了氨氧化古菌外，参与一氧化二氮产生和消耗的生物群落组成在营养物质富集的情况下发生了改变。这些结果表明，先前测得的一氧化二氮产生和消耗速率可能是群落结构变化的结果，而不仅仅是微生物活性的变化。
