Methanotrophy Alleviates Nitrogen Constraint of Carbon Turnover by Rice Root-Associated Microbiomes.
Methanotrophy Alleviates Nitrogen Constraint of Carbon Turnover by Rice Root-Associated Microbiomes.
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甲烷氧化减轻水稻根部相关微生物对碳周转的氮限制
DOI：
10.3389/fmicb.2022.885087
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发表时间：
2022
影响因子：
5.2
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中科院分区：
文献类型：
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氮的生物利用度限制了初级生产力，而生态系统化学计量意味着刺激氮固定与水稻土等热点地区的碳封存相关。在这项研究中，我们表明氮固定是由甲烷氧化引发的，甲烷氧化菌是驱动水稻根部碳和氮周转的微生物引擎。 15N2稳定同位素探测表明，CH4氧化作用使根系干重生物量从0.27μmol N g–1增加到43.3 μmol N g–1，固氮活性提高了160倍，并且大约42.5%的固定氮通过微生物矿化以 15N-NH4+ 的形式存在。硝酸盐修正几乎完全废除了 N2 固定。生态生理学通量测量表明，甲烷氧化诱导的固氮仅贡献总氮的1.9%，而甲烷氧化引发的矿化占总氮的21.7%，以促进根系碳周转。基于 DNA 的稳定同位素探测进一步表明，在消耗 CH4 的根中，γ 变形菌甲基单胞菌样甲烷氧化菌主导了 N2 固定，而硝酸盐的添加导致活跃群体转变为 α 变形菌甲基囊藻样甲烷氧化菌。活跃微生物群落的共生模式分析进一步表明，许多关键类群可能在通过根部分解和固氮获取氮素方面发挥着重要作用，以促进养分循环，同时保持土壤生产力。因此，这项研究强调了与根相关的甲烷氧化菌作为温室气体甲烷的生物过滤器和生物可利用氮的微生物引擎对水稻生长的重要性。
The bioavailability of nitrogen constrains primary productivity, and ecosystem stoichiometry implies stimulation of N2 fixation in association with carbon sequestration in hotspots such as paddy soils. In this study, we show that N2 fixation was triggered by methane oxidation and the methanotrophs serve as microbial engines driving the turnover of carbon and nitrogen in rice roots. 15N2-stable isotope probing showed that N2-fixing activity was stimulated 160-fold by CH4 oxidation from 0.27 to 43.3 μmol N g–1 dry weight root biomass, and approximately 42.5% of the fixed N existed in the form of 15N-NH4+ through microbial mineralization. Nitrate amendment almost completely abolished N2 fixation. Ecophysiology flux measurement indicated that methane oxidation-induced N2 fixation contributed only 1.9% of total nitrogen, whereas methanotrophy-primed mineralization accounted for 21.7% of total nitrogen to facilitate root carbon turnover. DNA-based stable isotope probing further indicated that gammaproteobacterial Methylomonas-like methanotrophs dominated N2 fixation in CH4-consuming roots, whereas nitrate addition resulted in the shift of the active population to alphaproteobacterial Methylocystis-like methanotrophs. Co-occurring pattern analysis of active microbial community further suggested that a number of keystone taxa could have played a major role in nitrogen acquisition through root decomposition and N2 fixation to facilitate nutrient cycling while maintaining soil productivity. This study thus highlights the importance of root-associated methanotrophs as both biofilters of greenhouse gas methane and microbial engines of bioavailable nitrogen for rice growth.