Evidence map›Paper›PMID 24591586›Full record

ArticleProceedings of the National Academy of Sciences of the United States of America2014

A soil actinobacterium scavenges atmospheric H2 using two membrane-associated, oxygen-dependent [NiFe] hydrogenases.

Chris Greening, Michael Berney, Kiel Hards, Gregory M Cook, Ralf Conrad

Open access · bronzeAbstract read
In one paragraph

Article in Proceedings of the National Academy of Sciences of the United States of America, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 81 papers.

0numbers the graph read from it
0cells of the map it votes in
81citing papers in PubMed
4.2field-weighted citation impact, top 5% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

81 citing papers in PubMed, 151 citations in OpenAlex.

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  11. ATP synthesis driven by atmospheric hydrogen concentrations.Proceedings of the National Academy of Sciences of the United States of America · 2025
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21 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors at 3 institutions in 3 countries.

Chris GreeningDepartment of Microbiology and Immunology, University of Otago, Dunedin 9016, New Zealand.
Michael Berney
Kiel Hards
Gregory M Cook
Ralf Conrad
Max Planck Institute for Terrestrial Microbiology · DEUniversity of Otago · NZAlbert Einstein College of Medicine · US

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

In the Earth's lower atmosphere, H2 is maintained at trace concentrations (0.53 ppmv/0.40 nM) and rapidly turned over (lifetime ≤ 2.1 y(-1)). It is thought that soil microbes, likely actinomycetes, serve as the main global sink for tropospheric H2. However, no study has ever unambiguously proven that a hydrogenase can oxidize this trace gas. In this work, we demonstrate, by using genetic dissection and sensitive GC measurements, that the soil actinomycete Mycobacterium smegmatis mc(2)155 constitutively oxidizes subtropospheric concentrations of H2. We show that two membrane-associated, oxygen-dependent [NiFe] hydrogenases mediate this process. Hydrogenase-1 (Hyd1) (MSMEG_2262-2263) is well-adapted to rapidly oxidize H2 at a range of concentrations [Vmax(app) = 12 nmol⋅g⋅dw(-1)⋅min(-1); Km(app) = 180 nM; threshold = 130 pM in the Δhyd23 (Hyd1 only) strain], whereas Hyd2 (MSMEG_2719-2720) catalyzes a slower-acting, higher-affinity process [Vmax(app) = 2.5 nmol⋅g⋅dw(-1)⋅min(-1); Km(app) = 50 nM; threshold = 50 pM in the Δhyd13 (Hyd2 only) strain]. These observations strongly support previous studies that have linked group 5 [NiFe] hydrogenases (e.g., Hyd2) to the oxidation of tropospheric H2 in soil ecosystems. We further reveal that group 2a [NiFe] hydrogenases (e.g., Hyd1) can contribute to this process. Hydrogenase expression and activity increases in carbon-limited cells, suggesting that scavenging of trace H2 helps to sustain dormancy. Distinct physiological roles for Hyd1 and Hyd2 during the adaptation to this condition are proposed. Soil organisms harboring high-affinity hydrogenases may be especially competitive, given that they harness a highly dependable fuel source in otherwise unstable environments.

Indexed as

Soil MicrobiologyAtmosphereChromatography, GasHydrogenHydrogenaseMycobacterium smegmatisOxidation-ReductionOxygenHydrogenHydrogenasenickel-iron hydrogenaseOxygenatmospheric chemistrybiogeochemical cyclesenzyme kineticsmycobacteria

Identifiers

PMID24591586
PMCPMC3964045
OpenAlexW2041527665

What OpenQuestion holds

Textmetadata
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.