韦革宏、陈卫民等《The ISME Journal》2023年

论文题目：Reduced trace gas oxidizers as a response to organic carbon availability linked to oligotrophs in desert fertile islands

论文作者：Shuyue Li，Shanshan Yang， Xiaomeng Wei，Shuo Jiao，Wen Luo，Weimin Chen，Gehong Wei

论文摘要：Atmospheric trace gases, such as H2and CO, are important energy sources for microbial growth and maintenance in various ecosystems, especially in arid deserts with little organic substrate. Nonetheless, the impact of soil organic C availability on microbial trace gas oxidation and the underlying mechanisms are unclear at the community level. This study investigated the energy and life-history strategies of soil microbiomes along an organic C gradient inside and out ofHedysarum scopariumislands dispersed in the Mu Us Desert, China. Metagenomic analysis showed that with increasing organic C availability from bare areas into “fertile islands”, the abundance of trace gas oxidizers (TGOs) decreased, but that of trace gas nonoxidizers (TGNOs) increased. The variation in their abundance was more related to labile/soluble organic C levels than to stable/insoluble organic C levels. The consumption rates of H2and CO confirmed that organic C addition, especially soluble organic C addition, inhibited microbial trace gas oxidation. Moreover, microorganisms with distinct energy-acquiring strategies showed different life-history traits. The TGOs had lower 16S rRNA operon copy numbers, lower predicted maximum growth rates and higher proportions of labile C degradation genes, implying the prevalence of oligotrophs. In contrast, copiotrophs were prevalent in the TGNOs. These results revealed a mechanism for the microbial community to adapt to the highly heterogeneous distribution of C resources by adjusting the abundances of taxa with distinct energy and life-history strategies, which would further affect trace gas consumption and C turnover in desert ecosystems.

大气微量气体，如H2和CO，是多种生态系统中微生物用于维持生存的重要能源物质，尤其是在有机质匮乏的干旱沙漠中。然而，土壤有机碳含量对微生物群落的微量气体利用能力的影响，以及产生影响的机制尚不明确。本研究以毛乌素沙地中的花棒（Hedysarumscoparium）“肥岛”为研究对象，探究了岛内、外的有机碳梯度上，土壤微生物群落的能量策略和生活史策略的变化。宏基因组分析表明，从“肥岛”外的裸露地区到岛内，随着有机碳含量及其生物有效性的增加，能够利用微量气体的微生物类群（TGOs）的丰度逐渐降低，而不能利用微量气体类群（TGNOs）的丰度逐渐升高。二者的丰度变化主要受到活性的可溶性有机碳含量的影响，与惰性的不溶性有机碳相关性较小。室内测定的H2和CO的氧化速率表明，添加外源有机碳，尤其是可溶性有机碳，能够显著抑制微生物对微量气体的氧化活性。此外，具有不同能量策略的微生物类群具有不同的生活史特征。TGOs具有较低的16SrRNA操纵子拷贝数和最大生长速率，其基因组中包含较高比例的惰性有机碳降解基因，这意味着该类群中寡营养微生物丰度较高。相反，富营养型微生物则在TGNOs中丰度更高。这些结果揭示了微生物群落通过调节群落成员的能量策略和生活史策略，来适应自然环境下碳资源的高度异质性的机制，而微生物能量和生活史策略的改变将进一步对沙漠生态系统的大气成分和物质循环产生影响。

论文链接：https://www.nature.com/articles/s41396-023-01437-6