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Open Access Publications from the University of California

The tale of a neglected energy source: Elevated hydrogen exposure affects both microbial diversity and function in soil

  • Author(s): Khdhiri, M
  • Piché-Choquette, S
  • Tremblay, J
  • Tringe, SG
  • Constant, P
  • et al.

© 2017 American Society for Microbiology. The enrichment of H2-oxidizing bacteria (HOB) by H2generated by nitrogenfixing nodules has been shown to have a fertilization effect on several different crops. The benefit of HOB is attributed to their production of plant growth-promoting factors, yet their interactions with other members of soil microbial communities have received little attention. Here we report that the energy potential of H2, when supplied to soil, alters ecological niche partitioning of bacteria and fungi, with multifaceted consequences for both generalist and specialist microbial functions. We used dynamic microcosms to expose soil to the typical atmospheric H2mixing ratio (0.5 ppmv) permeating soils, as well as mixing ratios comparable to those found at the soil-nodule interface (10,000 ppmv). Elevated H2exposure exerted direct effects on two HOB subpopulations distinguished by their affinity for H2while enhancing community level carbon substrate utilization potential and lowering CH4uptake activity in soil. We found that H2triggered changes in the abundance of microorganisms that were reproducible yet inconsistent across soils at the taxonomic level and even among HOB. Overall, H2exposure altered microbial process rates at an intensity that depends upon soil abiotic and biotic features. We argue that further examination of direct and indirect effects of H2on soil microbial communities will lead to a better understanding of the H2fertilization effect and soil biogeochemical processes.

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