Tag Archives: energy metabolism

Consumption of atmospheric hydrogen during the life cycle of soil-dwelling actinobacteria

The presence (left) or absence (right) of aerial hyphae in Streptomyces may influence their atmospheric H2 consumption

The presence (left) or absence (right) of aerial hyphae in Streptomyces may be linked to atmospheric H2 consumption

Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2). In a recent study (early view in Environmental Microbiology Reports), we probed the advantage of atmospheric H2 consumption to microbes and relationship between environmental conditions, physiology of soil microbes, and H2. First, we were interested in whether environmental isolates and culture collection strains with the genetic potential for atmospheric H2 uptake (a specific NiFe-hydrogenase gene) actually exhibit atmospheric H2 uptake. To expand the library of atmospheric H2-oxidizing bacteria, we quantify H2 uptake rates by novel Streptomyces soil isolates that contain the hhyL and by three previously isolated and sequenced strains of actinobacteria whose hhyL sequences span the known hhyL diversity. Second, we investigated how H2 uptake varies over organismal life cycle in one sporulating and one non-sporulating microorganism, Streptomyces sp. HFI8 and Rhodococcus equi, respectively. Our observations suggest that conditions favoring H2 uptake by actinobacteria are associated with energy and nutrient limitation. Thus, H2 may be an important energy source for soil microorganisms inhabiting systems in which nutrients are frequently limited.

Much of this work was done with the help of Deepa Rao, an undergraduate researcher at MIT at the time who wrote an award-winning senior thesis on the topic and presented results in a number of venues, including at AGU 2012.

 

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Atmospheric H2 energetic fertilization to soil microorganisms in a forest ecosystem

Poster presented at the Ecology of Soil Microorganisms conference in Prague, 2011:

Ecology of Soil Microorganisms poster

Ecology of Soil Microorganisms

TopicSoil microorganisms dominate the fate of atmospheric molecular hydrogen (H2 ) and comprise an estimated 75-80% of its global sink. Recent work has linked atmospheric H2 uptake to a novel high-affinity [NiFe]-hydrogenase expressed in active Streptomyces sp. cells [1], 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. Continue reading

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