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Ray AE, Tribbia DZ, Cowan DA, Ferrari BC. Clearing the air: unraveling past and guiding future research in atmospheric chemosynthesis. Microbiol Mol Biol Rev 2023; 87:e0004823. [PMID: 37914532 PMCID: PMC10732025 DOI: 10.1128/mmbr.00048-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023] Open
Abstract
SUMMARY Atmospheric chemosynthesis is a recently proposed form of chemoautotrophic microbial primary production. The proposed process relies on the oxidation of trace concentrations of hydrogen (≤530 ppbv), carbon monoxide (≤90 ppbv), and methane (≤1,870 ppbv) gases using high-affinity enzymes. Atmospheric hydrogen and carbon monoxide oxidation have been primarily linked to microbial growth in desert surface soils scarce in liquid water and organic nutrients, and low in photosynthetic communities. It is well established that the oxidation of trace hydrogen and carbon monoxide gases widely supports the persistence of microbial communities in a diminished metabolic state, with the former potentially providing a reliable source of metabolic water. Microbial atmospheric methane oxidation also occurs in oligotrophic desert soils and is widespread throughout copiotrophic environments, with established links to microbial growth. Despite these findings, the direct link between trace gas oxidation and carbon fixation remains disputable. Here, we review the supporting evidence, outlining major gaps in our understanding of this phenomenon, and propose approaches to validate atmospheric chemosynthesis as a primary production process. We also explore the implications of this minimalistic survival strategy in terms of nutrient cycling, climate change, aerobiology, and astrobiology.
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Affiliation(s)
- Angelique E. Ray
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, Australia
- Australian Centre for Astrobiology, UNSW Sydney, Sydney, Australia
| | - Dana Z. Tribbia
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, Australia
- Australian Centre for Astrobiology, UNSW Sydney, Sydney, Australia
| | - Don A. Cowan
- Centre for Microbial Ecology and Genomics, Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Belinda C. Ferrari
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, Australia
- Australian Centre for Astrobiology, UNSW Sydney, Sydney, Australia
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Meinel M, Delgado AG, Ilhan ZE, Aguero ML, Aguiar S, Krajmalnik-Brown R, Torres CI. Organic carbon metabolism is a main determinant of hydrogen demand and dynamics in anaerobic soils. CHEMOSPHERE 2022; 303:134877. [PMID: 35577129 DOI: 10.1016/j.chemosphere.2022.134877] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/29/2022] [Accepted: 05/04/2022] [Indexed: 06/15/2023]
Abstract
Hydrogen (H2) is a crucial electron donor for many processes in the environment including nitrate-, sulfate- and, iron-reduction, homoacetogenesis, and methanogenesis, and is a major determinant of microbial competition and metabolic pathways in groundwater, sediments, and soils. Despite the importance of H2 for many microbial processes in the environment, the total H2 consuming capacity (or H2 demand) of soils is generally unknown. Using soil microcosms with added H2, the aims of this study were 1) to measure the H2 demand of geochemically diverse soils and 2) to define the processes leading to this demand. Study results documented a large range of H2 demand in soil (0.034-1.2 millielectron equivalents H2 g-1 soil). The measured H2 demand greatly exceeded the theoretical demand predicted based on measured concentrations of common electron acceptors initially present in a library of 15 soils. While methanogenesis accounted for the largest fraction of H2 demand, humic acid reduction and acetogenesis were also significant contributing H2-consuming processes. Much of the H2 demand could be attributed to CO2 produced during incubation from fermentation and/or acetoclastic methanogenesis. The soil initial total organic carbon showed the strongest correlation to H2 demand. Besides external additions, H2 was likely generated or cycled in the microcosms. Apart from fermentative H2 production, carboxylate elongation to produce C4-C7 fatty acids may have accounted for additional H2 production in these soils. Many of these processes, especially the organic carbon contribution is underestimated in microbial models for H2 consumption in natural soil ecosystems or during bioremediation of contaminants in soils.
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Affiliation(s)
- Megan Meinel
- Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, School of Sustainable Engineering and the Built Environment, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), 1001 S McAllister Ave, Tempe, AZ, USA
| | - Anca G Delgado
- Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, School of Sustainable Engineering and the Built Environment, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), 1001 S McAllister Ave, Tempe, AZ, USA
| | - Zehra Esra Ilhan
- Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA
| | - Marisol Luna Aguero
- Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, School of Sustainable Engineering and the Built Environment, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), 1001 S McAllister Ave, Tempe, AZ, USA
| | - Samuel Aguiar
- Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), 1001 S McAllister Ave, Tempe, AZ, USA
| | - Rosa Krajmalnik-Brown
- Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, School of Sustainable Engineering and the Built Environment, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, Biodesign Center for Health Through Microbiomes, 1001 S McAllister Ave, Tempe, AZ, USA.
| | - César I Torres
- Arizona State University, Biodesign Swette Center for Environmental Biotechnology, 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, Engineering Research Center for Bio-mediated and Bio-inspired Geotechnics (CBBG), 1001 S McAllister Ave, Tempe, AZ, USA; Arizona State University, School for Engineering of Matter, Transport & Energy, 1001 S McAllister Ave, Tempe, AZ, USA.
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Buzzard V, Thorne D, Gil-Loaiza J, Cueva A, Meredith LK. Sensitivity of soil hydrogen uptake to natural and managed moisture dynamics in a semiarid urban ecosystem. PeerJ 2022; 10:e12966. [PMID: 35317075 PMCID: PMC8934528 DOI: 10.7717/peerj.12966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 01/28/2022] [Indexed: 01/11/2023] Open
Abstract
The North American Monsoon season (June-September) in the Sonoran Desert brings thunderstorms and heavy rainfall. These rains bring cooler temperature and account for roughly half of the annual precipitation making them important for biogeochemical processes. The intensity of the monsoon rains also increase flooding in urban areas and rely on green infrastructure (GI) stormwater management techniques such as water harvesting and urban rain gardens to capture runoff. The combination of increased water availability during the monsoon and water management provide a broad moisture regime for testing responses in microbial metabolism to natural and managed soil moisture pulses in drylands. Soil microbes rely on atmospheric hydrogen (H2) as an important energy source in arid and semiarid landscapes with low soil moisture and carbon availability. Unlike mesic ecosystems, transient water availability in arid and semiarid ecosystems has been identified as a key limiting driver of microbe-mediated H2 uptake. We measured soil H2 uptake in rain gardens exposed to three commonly used water harvesting practices during the monsoon season in Tucson AZ, USA. In situ static chamber measurements were used to calculate H2 uptake in each of the three water harvesting treatments passive (stormwater runoff), active (stored rooftop runoff), and greywater (used laundry water) compared to an unaltered control treatment to assess the effects of water management practices on soil microbial activity. In addition, soils were collected from each treatment and brought to the lab for an incubation experiment manipulating the soil moisture to three levels capturing the range observed from field samples. H2 fluxes from all treatments ranged between -0.72 nmol m-2 s-1 and -3.98 nmol m-2 s-1 over the monsoon season. Soil H2 uptake in the greywater treatment was on average 53% greater than the other treatments during pre-monsoon, suggesting that the increased frequency and availability of water in the greywater treatment resulted in higher H2 uptake during the dry season. H2 uptake was significantly correlated with soil moisture (r = -0.393, p = 0.001, df = 62) and temperature (r = 0.345, p = 0.005, df = 62). Our findings suggest that GI managed residential soils can maintain low levels of H2 uptake during dry periods, unlike unmanaged systems. The more continuous H2 uptake associated with GI may help reduce the impacts of drought on H2 cycling in semiarid urban ecosystems.
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Affiliation(s)
- Vanessa Buzzard
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States
| | - Dana Thorne
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States
| | - Juliana Gil-Loaiza
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States
| | - Alejandro Cueva
- Biosphere2, University of Arizona, Oracle, Arizona, United States
| | - Laura K. Meredith
- School of Natural Resources and the Environment, University of Arizona, Tucson, Arizona, United States,BIO5 Institute, University of Arizona, Tucson, Arizona, United States
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Ray AE, Zhang E, Terauds A, Ji M, Kong W, Ferrari BC. Soil Microbiomes With the Genetic Capacity for Atmospheric Chemosynthesis Are Widespread Across the Poles and Are Associated With Moisture, Carbon, and Nitrogen Limitation. Front Microbiol 2020; 11:1936. [PMID: 32903524 PMCID: PMC7437527 DOI: 10.3389/fmicb.2020.01936] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 07/22/2020] [Indexed: 11/13/2022] Open
Abstract
Soil microbiomes within oligotrophic cold deserts are extraordinarily diverse. Increasingly, oligotrophic sites with low levels of phototrophic primary producers are reported, leading researchers to question their carbon and energy sources. A novel microbial carbon fixation process termed atmospheric chemosynthesis recently filled this gap as it was shown to be supporting primary production at two Eastern Antarctic deserts. Atmospheric chemosynthesis uses energy liberated from the oxidation of atmospheric hydrogen to drive the Calvin-Benson-Bassham (CBB) cycle through a new chemotrophic form of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), designated IE. Here, we propose that the genetic determinants of this process; RuBisCO type IE (rbcL1E) and high affinity group 1h-[NiFe]-hydrogenase (hhyL) are widespread across cold desert soils and that this process is linked to dry and nutrient-poor environments. We used quantitative PCR (qPCR) to quantify these genes in 122 soil microbiomes across the three poles; spanning the Tibetan Plateau, 10 Antarctic and three high Arctic sites. Both genes were ubiquitous, being present at variable abundances in all 122 soils examined (rbcL1E, 6.25 × 103–1.66 × 109 copies/g soil; hhyL, 6.84 × 103–5.07 × 108 copies/g soil). For the Antarctic and Arctic sites, random forest and correlation analysis against 26 measured soil physicochemical parameters revealed that rbcL1E and hhyL genes were associated with lower soil moisture, carbon and nitrogen content. While further studies are required to quantify the rates of trace gas carbon fixation and the organisms involved, we highlight the global potential of desert soil microbiomes to be supported by this new minimalistic mode of carbon fixation, particularly throughout dry oligotrophic environments, which encompass more than 35% of the Earth’s surface.
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Affiliation(s)
- Angelique E Ray
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Eden Zhang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Aleks Terauds
- Australian Antarctic Division, Department of Environment, Antarctic Conservation and Management, Kingston, TAS, Australia
| | - Mukan Ji
- Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Weidong Kong
- Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Belinda C Ferrari
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
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de la Porte A, Schmidt R, Yergeau É, Constant P. A Gaseous Milieu: Extending the Boundaries of the Rhizosphere. Trends Microbiol 2020; 28:536-542. [PMID: 32544440 DOI: 10.1016/j.tim.2020.02.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 11/07/2019] [Accepted: 02/24/2020] [Indexed: 11/30/2022]
Abstract
Plant root activities shape microbial community functioning in the soil, making the rhizosphere the epicenter of soil biogeochemical processes. With this opinion article, we argue to rethink the rhizosphere boundaries: as gases can diffuse several centimeters away from the roots into the soil, the portion of soil influenced by root activities is larger than the strictly root-adhering soil. Indeed, gases are key drivers of biogeochemical processes due to their roles as energy sources or communication molecules, which has the potential to modify microbial community structure and functioning. In order to get a more holistic perspective on this key environment, we advocate for interdisciplinarity in rhizosphere research by combining knowledge of soluble compounds with gas dynamics.
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Affiliation(s)
- Anne de la Porte
- Institut National de la Recherche Scientifique, Centre Armand-Frappier Santé Biotechnologie, Laval, H7V 1B7, Canada; Quebec Center for Biodiversity Sciences (QCBS), Montreal, H3A 1B1, Canada
| | - Ruth Schmidt
- Institut National de la Recherche Scientifique, Centre Armand-Frappier Santé Biotechnologie, Laval, H7V 1B7, Canada; Quebec Center for Biodiversity Sciences (QCBS), Montreal, H3A 1B1, Canada.
| | - Étienne Yergeau
- Institut National de la Recherche Scientifique, Centre Armand-Frappier Santé Biotechnologie, Laval, H7V 1B7, Canada; Quebec Center for Biodiversity Sciences (QCBS), Montreal, H3A 1B1, Canada
| | - Philippe Constant
- Institut National de la Recherche Scientifique, Centre Armand-Frappier Santé Biotechnologie, Laval, H7V 1B7, Canada; Quebec Center for Biodiversity Sciences (QCBS), Montreal, H3A 1B1, Canada
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The Tale of a Neglected Energy Source: Elevated Hydrogen Exposure Affects both Microbial Diversity and Function in Soil. Appl Environ Microbiol 2017; 83:AEM.00275-17. [PMID: 28363961 DOI: 10.1128/aem.00275-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/27/2017] [Indexed: 11/20/2022] Open
Abstract
The enrichment of H2-oxidizing bacteria (HOB) by H2 generated by nitrogen-fixing 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 H2 mixing ratio (0.5 ppmv) permeating soils, as well as mixing ratios comparable to those found at the soil-nodule interface (10,000 ppmv). Elevated H2 exposure exerted direct effects on two HOB subpopulations distinguished by their affinity for H2 while enhancing community level carbon substrate utilization potential and lowering CH4 uptake activity in soil. We found that H2 triggered changes in the abundance of microorganisms that were reproducible yet inconsistent across soils at the taxonomic level and even among HOB. Overall, H2 exposure 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 H2 on soil microbial communities will lead to a better understanding of the H2 fertilization effect and soil biogeochemical processes.IMPORTANCE An innovative dynamic microcosm chamber system was used to demonstrate that H2 diffusing in soil triggers changes in the distribution of HOB and non-HOB. Although the response was uneven at the taxonomic level, an unexpected coordinated response of microbial functions was observed, including abatement of CH4 oxidation activity and stimulation of carbon turnover. Our work suggests that elevated H2 rewires soil biogeochemical structure through a combination of direct effects on the growth and persistence of HOB and indirect effects on a variety of microbial processes involving HOB and non-HOB.
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Meredith LK, Commane R, Keenan TF, Klosterman ST, Munger JW, Templer PH, Tang J, Wofsy SC, Prinn RG. Ecosystem fluxes of hydrogen in a mid-latitude forest driven by soil microorganisms and plants. GLOBAL CHANGE BIOLOGY 2017; 23:906-919. [PMID: 27514856 DOI: 10.1111/gcb.13463] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 07/22/2016] [Accepted: 07/29/2016] [Indexed: 06/06/2023]
Abstract
Molecular hydrogen (H2 ) is an atmospheric trace gas with a large microbe-mediated soil sink, yet cycling of this compound throughout ecosystems is poorly understood. Measurements of the sources and sinks of H2 in various ecosystems are sparse, resulting in large uncertainties in the global H2 budget. Constraining the H2 cycle is critical to understanding its role in atmospheric chemistry and climate. We measured H2 fluxes at high frequency in a temperate mixed deciduous forest for 15 months using a tower-based flux-gradient approach to determine both the soil-atmosphere and the net ecosystem flux of H2 . We found that Harvard Forest is a net H2 sink (-1.4 ± 1.1 kg H2 ha-1 ) with soils as the dominant H2 sink (-2.0 ± 1.0 kg H2 ha-1 ) and aboveground canopy emissions as the dominant H2 source (+0.6 ± 0.8 kg H2 ha-1 ). Aboveground emissions of H2 were an unexpected and substantial component of the ecosystem H2 flux, reducing net ecosystem uptake by 30% of that calculated from soil uptake alone. Soil uptake was highly seasonal (July maximum, February minimum), positively correlated with soil temperature and negatively correlated with environmental variables relevant to diffusion into soils (i.e., soil moisture, snow depth, snow density). Soil microbial H2 uptake was correlated with rhizosphere respiration rates (r = 0.8, P < 0.001), and H2 metabolism yielded up to 2% of the energy gleaned by microbes from carbon substrate respiration. Here, we elucidate key processes controlling the biosphere-atmosphere exchange of H2 and raise new questions regarding the role of aboveground biomass as a source of atmospheric H2 and mechanisms linking soil H2 and carbon cycling. Results from this study should be incorporated into modeling efforts to predict the response of the H2 soil sink to changes in anthropogenic H2 emissions and shifting soil conditions with climate and land-use change.
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Affiliation(s)
- Laura K Meredith
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA
- Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Róisín Commane
- Department of Earth and Planetary Science, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Trevor F Keenan
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Stephen T Klosterman
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - J William Munger
- Department of Earth and Planetary Science, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | | | - Jianwu Tang
- Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA, USA
| | - Steven C Wofsy
- Department of Earth and Planetary Science, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Ronald G Prinn
- Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, Cambridge, MA, USA
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Abstract
We have known for 40 years that soils can consume the trace amounts of molecular hydrogen (H2) found in the Earth’s atmosphere.This process is predicted to be the most significant term in the global hydrogen cycle. However, the organisms and enzymes responsible for this process were only recently identified. Pure culture experiments demonstrated that several species of Actinobacteria, including streptomycetes and mycobacteria, can couple the oxidation of atmospheric H2 to the reduction of ambient O2. A combination of genetic, biochemical, and phenotypic studies suggest that these organisms primarily use this fuel source to sustain electron input into the respiratory chain during energy starvation. This process is mediated by a specialized enzyme, the group 5 [NiFe]-hydrogenase, which is unusual for its high affinity, oxygen insensitivity, and thermostability. Atmospheric hydrogen scavenging is a particularly dependable mode of energy generation, given both the ubiquity of the substrate and the stress tolerance of its catalyst. This minireview summarizes the recent progress in understanding how and why certain organisms scavenge atmospheric H2. In addition, it provides insight into the wider significance of hydrogen scavenging in global H2 cycling and soil microbial ecology.
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Meredith LK, Rao D, Bosak T, Klepac-Ceraj V, Tada KR, Hansel CM, Ono S, Prinn RG. Consumption of atmospheric hydrogen during the life cycle of soil-dwelling actinobacteria. ENVIRONMENTAL MICROBIOLOGY REPORTS 2014; 6:226-238. [PMID: 24983527 DOI: 10.1111/1758-2229.12116] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 10/13/2013] [Indexed: 06/03/2023]
Abstract
Microbe-mediated soil uptake is the largest and most uncertain variable in the budget of atmospheric hydrogen (H2 ). The diversity and ecophysiological role of soil microorganisms that can consume low atmospheric abundances of H2 with high-affinity [NiFe]-hydrogenases is unknown. We expanded the library of atmospheric H2 -consuming strains to include four soil Harvard Forest Isolate (HFI) Streptomyces spp., Streptomyces cattleya and Rhodococcus equi by assaying for high-affinity hydrogenase (hhyL) genes and quantifying H2 uptake rates. We find that aerial structures (hyphae and spores) are important for Streptomyces H2 consumption; uptake was not observed in S. griseoflavus Tu4000 (deficient in aerial structures) and was reduced by physical disruption of Streptomyces sp. HFI8 aerial structures. H2 consumption depended on the life cycle stage in developmentally distinct actinobacteria: Streptomyces sp. HFI8 (sporulating) and R. equi (non-sporulating, non-filamentous). Strain HFI8 took up H2 only after forming aerial hyphae and sporulating, while R. equi only consumed H2 in the late exponential and stationary phase. These observations suggest that conditions favouring 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.
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Affiliation(s)
- Laura K Meredith
- Massachusetts Institute of Technology, Department of Earth, Atmospheric and Planetary Science, Cambridge, MA, 02139, USA
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Constant P, Poissant L, Villemur R. Tropospheric H(2) budget and the response of its soil uptake under the changing environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2009; 407:1809-1823. [PMID: 19155054 DOI: 10.1016/j.scitotenv.2008.10.064] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 10/06/2008] [Accepted: 10/26/2008] [Indexed: 05/27/2023]
Abstract
Molecular hydrogen (H(2)) is an indirect greenhouse gas present at the trace level in the atmosphere. So far, the sum of its sources and sinks is close to equilibrium, but its large-scale utilization as an alternative energy carrier would alter its atmospheric burden. The magnitude of the emissions associated with a future H(2)-based economy is difficult to predict and remains a matter of debate. Previous attempts to predict the impact that a future H(2)-based economy would exert on tropospheric chemistry were realized by considering a steady rate of microbial-mediated soil uptake, which is currently responsible of ~80% of the tropospheric H(2) losses. Although soil uptake, also known as dry deposition is the most important sink for tropospheric H(2), microorganisms involved in the activity remain elusive. Given that microbial-mediated H(2) soil uptake is influenced by several environmental factors, global change should exert a significant effect on the activity and then, assuming a steady H(2) soil uptake rate for the future may be mistaken. Here, we present an overview of tropospheric H(2) sources and sinks with an emphasis on microbial-mediated soil uptake process. Future researches are proposed to investigate the influence that global change would exert on H(2) dry deposition and to identify microorganisms involved H(2) soil uptake activity.
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Affiliation(s)
- Philippe Constant
- INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, Québec, Canada H7V 1B7.
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