Microbial-mediated soil uptake accounts for ∼80% of the global tropospheric dihydrogen (H2) sinks. Studies conducted over the last three decades provide indirect evidences that H2 soil uptake is mediated by free soil hydrogenases or by unknown microorganisms that have a high affinity for H2. The exact nature of these hypothetical free soil enzymes or of H2-consuming microorganisms remains elusive because the activity has never been observed in pure culture. Here, we present the first aerobic microorganism able to consume tropospheric H2 at ambient levels. A dynamic microcosm chamber was developed to enrich a microbial consortium with a high affinity for H2, from which selected bacterial and fungal strains were isolated and tested for H2 uptake. Strain PCB7 had a H2 consumption activity that followed a Michaelis-Menten kinetics, with an apparent K(m) of 11p.p.m.v. and a H2 threshold concentration <0.100p.p.m.v., corresponding to the high-affinity uptake of tropospheric H2 observed in soil. 16S ribosomal RNA gene sequences showed that strain PCB7 is highly related to several Streptomyces species. H2 consumption occurred during the sporulation period of the bacterium. Addition of nickel increased the activity, suggesting that the enzymes involved in H2 consumption belong to the NiFe uptake class of hydrogenases. Because this is the first microorganism showing a high-affinity uptake of tropospheric H2, we anticipate that Streptomyces sp. PCB7 will become a model organism for the understanding of the environmental factors influencing H2 soil uptake. © 2008 International Society for Microbial Ecology All rights reserved.
CITATION STYLE
Constant, P., Poissant, L., & Villemur, R. (2008). Isolation of Streptomyces sp. PCB7, the first microorganism demonstrating high-affinity uptake of tropospheric H2. ISME Journal, 2(10), 1066–1076. https://doi.org/10.1038/ismej.2008.59
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