Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 1–1–1 Tennodai, Tsukuba, Ibaraki 305–8572, Japan.
Microbes Environ. 2010;25(3):156-63. doi: 10.1264/jsme2.me10120.
The community structure of methane-oxidizing bacteria (methanotrophs) is affected by concentrations of methane and oxygen. In rice fields, concentrations of both gases differ significantly between the flooded and drained seasons. We investigated the active methanotrophic community structures in flooded and drained soils by DNA-based stable isotope probing. Active methanotrophic diversity was assessed with clone library-based analyses of the 16S rRNA gene and the particulate methane monooxygenase gene (pmoA). The active methanotrophic populations were also estimated by group-specific quantitative real-time PCR assays targeting the 16S rRNA gene and the pmoA gene in (13)C-labeled DNA. These molecular biological analyses showed that the flooded rice field soil was dominated by Type II methanotrophs closely related to the genera Methylocystis and Methylosinus, whereas the drained rice field soil was dominated by Type I methanotrophs closely related to the genera Methylomonas, Methylosarcina, and Methylomicrobium. The alternating conditions in a rice field select for methanotrophs adapted to each environment, resulting in a dramatic change in methanotrophic community structure from one season to another.
甲烷氧化菌（甲烷营养菌）的群落结构受甲烷和氧气浓度的影响。在稻田中，这两种气体的浓度在淹水和排水季节有很大的差异。我们通过基于 DNA 的稳定同位素探针研究了淹水和排水土壤中的活性甲烷营养菌群落结构。通过克隆文库分析 16S rRNA 基因和颗粒态甲烷单加氧酶基因（pmoA）评估了活性甲烷营养菌的多样性。还通过针对标记的 (13)C DNA 的 16S rRNA 基因和 pmoA 基因的特异性定量实时 PCR 检测来估计活性甲烷营养菌的数量。这些分子生物学分析表明，淹水稻田土壤主要由与甲基球菌属和甲基单胞菌属密切相关的 II 型甲烷营养菌主导，而排水稻田土壤则主要由与甲基单胞菌属、甲基弧菌属和甲基微菌属密切相关的 I 型甲烷营养菌主导。稻田中的交替条件选择适应每种环境的甲烷营养菌，导致甲烷营养菌群落结构从一个季节到另一个季节发生巨大变化。
