Large amounts of H₂ are produced in the nodules of legume plants during N₂-fixation, which often subsequently leaks to the surrounding soil environment. This leaked H₂ activates H₂-oxidizing bacterial (HOB) communities and thus can alter microbial community structure and soil carbon and nitrogen turnover; a process that may explain part of the positive effect of crop rotations with legumes. We tested this hypothesis in the field by infusing H₂ in soil for 4 weeks and followed the effect on bacterial, archaeal and fungal communities by amplicon sequencing, as well as the abundance of genes involved in the nitrogen cycle using quantitative real-time PCR (qPCR). Soil exposure to elevated H₂ levels changed the capacity of soil to scavenge H₂ with a stimulation of low-affinity H₂-oxidizing activity. Activation of this functional group of bacteria led to significant increases in the relative abundance of Nitrososphaera, Gaiella and Gp16 in soil bacterial and archaeal communities, albeit without changing their diversity. In contrast, H₂ infusion had little effect on fungal community diversity, composition and taxa abundance. The abundance of selected functional genes encoding for bacterial and archaeal enzymes involved in the nitrogen cycle was not influenced by H₂ infusion, but the abundance of nifH was significantly affected by H₂ infusion × sampling date interaction. Variation in the high-affinity and low-affinity HOB, microbial community diversity and composition, and N-cycle gene abundance between sampling dates was attributed, in part, to significant differences in soil moisture during the study. Together, this work confirms that microbial taxa differ in their reaction to H₂ exposure in the field, and provides the first evidence that nitrifier and denitrifier microorganisms have uneven responses to elevated H₂ levels under field conditions.

在N ₂固定期间，豆类植物的结节中会产生大量H ₂，然后经常泄漏到周围的土壤环境中。这种泄漏的H ₂激活了H ₂氧化细菌（HOB）群落，因此可以改变微生物群落结构以及土壤碳氮交换。这个过程可以解释豆类作物轮作的积极影响的一部分。我们通过在土壤中注入H ₂ 4周来在田间测试了这一假设，然后通过扩增子测序以及使用实时定量PCR（PCR）对氮循环中涉及的大量基因进行了追踪，从而观察了对细菌，古细菌和真菌群落的影响（ qPCR）。土壤暴露于高H ₂水平的变化改变了土壤对H _2的清除能力，并刺激了低亲和力的H ₂氧化活性。细菌的这种官能团的活化导致的相对丰度显著上升Nitrososphaera，Gaiella和GP16在土壤中的细菌和古细菌群落，虽然没有改变他们的多样性。相比之下，H ₂注入对真菌群落多样性，组成和分类单元的丰度影响很小。选择的编码细菌和古细菌酶的功能基因的丰度与氮循环有关，不受H ₂注入的影响，但nifH的丰度影响H ₂注入×采样日期交互作用显着影响。采样日期之间高亲和力和低亲和力HOB，微生物群落多样性和组成以及N循环基因丰度的变化部分归因于研究期间土壤水分的显着差异。总之，这项工作证实了微生物分类单元对田间H ₂暴露的反应不同，并提供了第一个证据，证明硝化和反硝化微生物对田间条件下H ₂水平升高的反应不均匀。