Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
ISME J. 2010 Dec;4(12):1545-56. doi: 10.1038/ismej.2010.89. Epub 2010 Jul 1.
Nitrogen, one of the limiting factors for the yield of rice, can also have an important function in methane oxidation, thus affecting its global budget. Rice microcosms, planted in the greenhouse, were treated with the N-fertilizers urea (UPK) and ammonium sulfate (APK) or were only treated with phosphorous and potassium (PK). Methane oxidation rates in PK and UPK treatments were similar during most of the rice-growing season, revealing no effect of urea. However, ammonium sulfate strongly suppressed methanogenesis providing an unfavorable environment for methanotrophs in APK treatment. Roots and rhizospheric soil samples, collected from six different growth stages of the rice plant, were analyzed by terminal restriction fragment length polymorphism (T-RFLP) of the pmoA gene. Assignment of abundant T-RFs to cloned pmoA sequences indicated that the populations on roots were dominated by type-I methanotrophs, whereas the populations in rhizospheric soil were dominated by type-II methanotrophs irrespectively of growth stages and fertilizer treatments. Non-metric multidimensional scaling ordination analysis of T-RFLP profiles revealed that the methanotrophic community was significantly (P<0.001) affected by the different fertilizer treatments; however, the effect was stronger on the roots than in the rhizospheric soil. Contrary to pmoA gene-based analysis, pmoA transcript-based T-RFLP/cloning/sequencing analysis in rhizospheric soil showed type I as the predominant methanotrophs in both PK and UPK treatments. Collectively, our study showed that type-I methanotrophs were dominant and probably active in rhizospheric soil throughout the season irrespective of nitrogen fertilizer used, whereas type-II methanotrophs were relatively more dominant under unfavorable conditions, such as in APK treatment.
氮是限制水稻产量的因素之一，它在甲烷氧化中也具有重要作用，从而影响其全球预算。在温室中种植的水稻微宇宙分别用氮肥尿素（UPK）和硫酸铵（APK）处理，或只用磷钾（PK）处理。在水稻生长季节的大部分时间里，PK 和 UPK 处理中的甲烷氧化率相似，表明尿素没有影响。然而，硫酸铵强烈抑制了产甲烷作用，为 APK 处理中的甲烷营养菌提供了不利的环境。从水稻生长的六个不同阶段采集根和根际土壤样本，通过 pmoA 基因末端限制性片段长度多态性（T-RFLP）进行分析。将丰富的 T-RF 分配给克隆的 pmoA 序列表明，根上的种群主要由 I 型甲烷营养菌主导，而根际土壤中的种群主要由 II 型甲烷营养菌主导，与生长阶段和肥料处理无关。T-RFLP 图谱的非度量多维标度排序分析表明，不同肥料处理显著（P<0.001）影响了甲烷营养菌群落；然而，这种影响在根上比在根际土壤中更强。与 pmoA 基因分析相反，根际土壤中基于 pmoA 转录物的 T-RFLP/克隆/测序分析表明，I 型是 PK 和 UPK 处理中主要的甲烷营养菌。总的来说，我们的研究表明，I 型甲烷营养菌在整个季节中都是优势和活跃的，而在 APK 处理等不利条件下，II 型甲烷营养菌相对更占优势。
