College of Resources and Environmental Sciences, China Agricultural University, Beijing, China.
Appl Environ Microbiol. 2013 Aug;79(16):4932-9. doi: 10.1128/AEM.00850-13. Epub 2013 Jun 14.
The methanotrophs in rice field soil are crucial in regulating the emission of methane. Drainage substantially reduces methane emission from rice fields. However, it is poorly understood how drainage affects microbial methane oxidation. Therefore, we analyzed the dynamics of methane oxidation rates, composition (using terminal restriction fragment length polymorphism [T-RFLP]), and abundance (using quantitative PCR [qPCR]) of methanotroph pmoA genes (encoding a subunit of particulate methane monooxygenase) and their transcripts over the season and in response to alternate dry/wet cycles in planted paddy field microcosms. In situ methane oxidation accounted for less than 15% of total methane production but was enhanced by intermittent drainage. The dry/wet alternations resulted in distinct effects on the methanotrophic communities in different soil compartments (bulk soil, rhizosphere soil, surface soil). The methanotrophic communities of the different soil compartments also showed distinct seasonal dynamics. In bulk soil, potential methanotrophic activity and transcription of pmoA were relatively low but were significantly stimulated by drainage. In contrast, however, in the rhizosphere and surface soils, potential methanotrophic activity and pmoA transcription were relatively high but decreased after drainage events and resumed after reflooding. While type II methanotrophs dominated the communities in the bulk soil and rhizosphere soil compartments (and to a lesser extent also in the surface soil), it was the pmoA of type I methanotrophs that was mainly transcribed under flooded conditions. Drainage affected the composition of the methanotrophic community only minimally but strongly affected metabolically active methanotrophs. Our study revealed dramatic dynamics in the abundance, composition, and activity of the various type I and type II methanotrophs on both a seasonal and a spatial scale and showed strong effects of dry/wet alternation cycles, which enhanced the attenuation of methane flux into the atmosphere.
稻田土壤中的产甲烷菌在调节甲烷排放方面起着至关重要的作用。排水可显著减少稻田甲烷排放。然而，排水如何影响微生物甲烷氧化过程仍知之甚少。因此，我们分析了种植稻田微宇宙中甲烷氧化速率、组成（使用末端限制性片段长度多态性 [T-RFLP]）和丰度（使用定量 PCR [qPCR]）的季节性动态以及对交替干湿循环的响应，这些甲烷氧化菌的 pmoA 基因（编码颗粒态甲烷单加氧酶的一个亚基）。原位甲烷氧化仅占总甲烷生成量的不到 15%，但间歇性排水会增强其活性。干湿交替对不同土壤区室（原状土、根际土、表土）中的产甲烷菌群落产生了不同的影响。不同土壤区室的产甲烷菌群落也表现出明显的季节性动态。在原状土中，潜在的产甲烷活性和 pmoA 转录相对较低，但排水会显著刺激其活性。相比之下，在根际土和表土中，潜在的产甲烷活性和 pmoA 转录相对较高，但排水后会下降，再灌后会恢复。虽然 II 型产甲烷菌在原状土和根际土区室中占主导地位（在一定程度上也在表土中占主导地位），但在水淹条件下主要转录的是 I 型产甲烷菌的 pmoA。排水对产甲烷菌群落组成的影响很小，但对代谢活跃的产甲烷菌影响很大。我们的研究揭示了不同 I 型和 II 型产甲烷菌在数量、组成和活性方面的剧烈动态变化，以及干湿交替循环的强烈影响，这增强了甲烷通量向大气中的衰减。
