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Krichels AH, Jenerette GD, Shulman H, Piper S, Greene AC, Andrews HM, Botthoff J, Sickman JO, Aronson EL, Homyak PM. Bacterial denitrification drives elevated N 2O emissions in arid southern California drylands. SCIENCE ADVANCES 2023; 9:eadj1989. [PMID: 38055826 DOI: 10.1126/sciadv.adj1989] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 11/07/2023] [Indexed: 12/08/2023]
Abstract
Soils are the largest source of atmospheric nitrous oxide (N2O), a powerful greenhouse gas. Dry soils rarely harbor anoxic conditions to favor denitrification, the predominant N2O-producing process, yet, among the largest N2O emissions have been measured after wetting summer-dry desert soils, raising the question: Can denitrifiers endure extreme drought and produce N2O immediately after rainfall? Using isotopic and molecular approaches in a California desert, we found that denitrifiers produced N2O within 15 minutes of wetting dry soils (site preference = 12.8 ± 3.92 per mil, δ15Nbulk = 18.6 ± 11.1 per mil). Consistent with this finding, we detected nitrate-reducing transcripts in dry soils and found that inhibiting microbial activity decreased N2O emissions by 59%. Our results suggest that despite extreme environmental conditions-months without precipitation, soil temperatures of ≥40°C, and gravimetric soil water content of <1%-bacterial denitrifiers can account for most of the N2O emitted when dry soils are wetted.
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Affiliation(s)
- Alexander H Krichels
- Environmental Sciences, University of California, Riverside, CA, USA
- Center for Conservation Biology, University of California, Riverside, CA, USA
- USDA Rocky Mountain Research Station, Albuquerque, NM, USA
| | - G Darrel Jenerette
- Center for Conservation Biology, University of California, Riverside, CA, USA
- Botany and Plant Sciences, University of California, Riverside, CA, USA
| | - Hannah Shulman
- Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA
- Microbiology and Plant Pathology, University of California, Riverside, CA, USA
| | - Stephanie Piper
- Botany and Plant Sciences, University of California, Riverside, CA, USA
- Houston Advanced Research Center, The Woodlands, TX, USA
| | - Aral C Greene
- Environmental Sciences, University of California, Riverside, CA, USA
| | - Holly M Andrews
- Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA
- Geography, Development and Environment, University of Arizona, Tucson, AZ, USA
| | - Jon Botthoff
- Center for Conservation Biology, University of California, Riverside, CA, USA
| | - James O Sickman
- Environmental Sciences, University of California, Riverside, CA, USA
| | - Emma L Aronson
- Microbiology and Plant Pathology, University of California, Riverside, CA, USA
| | - Peter M Homyak
- Environmental Sciences, University of California, Riverside, CA, USA
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Gonzalez JM, Santana MM, Gomez EJ, Delgado JA. Soil Thermophiles and Their Extracellular Enzymes: A Set of Capabilities Able to Provide Significant Services and Risks. Microorganisms 2023; 11:1650. [PMID: 37512823 PMCID: PMC10386326 DOI: 10.3390/microorganisms11071650] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/30/2023] Open
Abstract
During this century, a number of reports have described the potential roles of thermophiles in the upper soil layers during high-temperature periods. This study evaluates the capabilities of these microorganisms and proposes some potential consequences and risks associated with the activity of soil thermophiles. They are active in organic matter mineralization, releasing inorganic nutrients (C, S, N, P) that otherwise remain trapped in the organic complexity of soil. To process complex organic compounds in soils, these thermophiles require extracellular enzymes to break down large polymers into simple compounds, which can be incorporated into the cells and processed. Soil thermophiles are able to adapt their extracellular enzyme activities to environmental conditions. These enzymes can present optimum activity under high temperatures and reduced water content. Consequently, these microorganisms have been shown to actively process and decompose substances (including pollutants) under extreme conditions (i.e., desiccation and heat) in soils. While nutrient cycling is a highly beneficial process to maintain soil service quality, progressive warming can lead to excessive activity of soil thermophiles and their extracellular enzymes. If this activity is too high, it may lead to reduction in soil organic matter, nutrient impoverishment and to an increased risk of aridity. This is a clear example of a potential effect of future predicted climate warming directly caused by soil microorganisms with major consequences for our understanding of ecosystem functioning, soil health and the risk of soil aridity.
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Affiliation(s)
- Juan M Gonzalez
- Institute of Natural Resources and Agrobiology, IRNAS-CSIC, Avda. Reina Mercedes 10, E-41012 Sevilla, Spain
| | - Margarida M Santana
- Centre for Ecology, Evolution and Environmental Changes (cE3c) & Global Change and Sustainability Institute (CHANGE), Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - Enrique J Gomez
- Institute of Natural Resources and Agrobiology, IRNAS-CSIC, Avda. Reina Mercedes 10, E-41012 Sevilla, Spain
| | - José A Delgado
- Department of Engineering, University of Loyola, Avda. de las Universidades, E-41704 Dos Hermanas, Spain
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