I presented a poster at the at the Ecology of Soil Microorganisms conference in Prague, 2011 on the role of soil microorganisms in dominating the fate of atmospheric molecular hydrogen (H2). Recent work has linked atmospheric H2 uptake to a novel high-affinity [NiFe]-hydrogenase expressed in active Streptomyces sp. cells, and is perhaps not driven by abiotic hydrogenases as was previously thought. Consequently, atmospheric hydrogen may be a 60-85 Tg yr-1 energetic supplement to microbes in Earth’s uppermost soil horizon. To understand the role of this supplement to the soil microbial ecology, this work explores the following questions: What is the importance of atmospheric H2 energy to soil microbial communities relative to…