CSIRO, Marine and Atmospheric Research and Wealth from Oceans, National Research Flagship, Hobart, Tasmania, Australia.
ISME J. 2010 Feb;4(2):286-300. doi: 10.1038/ismej.2009.105. Epub 2009 Oct 1.
Nitrification and denitrification are key steps in nitrogen (N) cycling. The coupling of these processes, which affects the flow of N in ecosystems, requires close interaction of nitrifying and denitrifying microorganisms, both spatially and temporally. The diversity, temporal and spatial variations in the microbial communities affecting these processes was examined, in relation to N cycling, across 12 sites in the Fitzroy river estuary, which is a turbid subtropical estuary in central Queensland. The estuary is a major source of nutrients discharged to the Great Barrier Reef near-shore zone. Measurement of nitrogen fluxes showed an active denitrifying community during all sampling months. Archaeal ammonia monooxygenase (amoA of AOA, functional marker for nitrification) was significantly more abundant than Betaproteobacterial (beta-AOB) amoA. Nitrite reductase genes, functional markers for denitrification, were dominated by nirS and not nirK types at all sites during the year. AOA communities were dominated by the soil/sediment cluster of Crenarchaeota, with sequences found in estuarine sediment, marine and terrestrial environments, whereas nirS sequences were significantly more diverse (where operational taxonomic units were defined at both the threshold of 5% and 15% sequence similarity) and were closely related to sequences originating from estuarine sediments. Terminal-restriction fragment length polymorphism (T-RFLP) analysis revealed that AOA population compositions varied spatially along the estuary, whereas nirS populations changed temporally. Statistical analysis of individual T-RF dominance suggested that salinity and C:N were associated with the community succession of AOA, whereas the nirS-type denitrifier communities were related to salinity and chlorophyll-alpha in the Fitzroy river estuary.
硝化和反硝化是氮（N）循环的关键步骤。这些过程的耦合影响着生态系统中 N 的流动，需要硝化和反硝化微生物在空间和时间上的紧密相互作用。本研究调查了与氮循环有关的、影响这些过程的微生物群落的多样性、时空变化，在昆士兰州中部的菲茨罗伊河口的 12 个地点进行。该河口是向大堡礁近岸区排放营养物质的主要来源。氮通量的测量表明，在所有采样月份都存在活跃的反硝化群落。古菌氨单加氧酶（AOA 的 amoA，硝化功能标记物）的丰度明显高于β变形菌（beta-AOB）amoA。硝酸盐还原酶基因（nirS 和 nirK 型）是反硝化的功能标记物，在一年中的所有地点均以 nirS 为主，而不是 nirK 型。AOA 群落主要由土壤/沉积物古菌群组成，在河口沉积物、海洋和陆地环境中都发现了这些序列，而 nirS 序列的多样性明显更高（在 5%和 15%序列相似性的阈值下定义操作分类单元），与源自河口沉积物的序列密切相关。末端限制性片段长度多态性（T-RFLP）分析表明，AOA 种群的组成沿河口空间上发生变化，而 nirS 种群随时间发生变化。个体 T-RF 优势的统计分析表明，盐度和 C:N 与 AOA 的群落演替有关，而 nirS 型反硝化菌群落与菲茨罗伊河口的盐度和叶绿素-α有关。
