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Temperature sensitivities of extracellular enzyme Vmax and Km across thermal environments.
Allison, Steven D; Romero-Olivares, Adriana L; Lu, Ying; Taylor, John W; Treseder, Kathleen K.
Afiliación
  • Allison SD; Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA.
  • Romero-Olivares AL; Department of Earth System Science, University of California, Irvine, CA, USA.
  • Lu Y; Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA.
  • Taylor JW; Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA.
  • Treseder KK; Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.
Glob Chang Biol ; 24(7): 2884-2897, 2018 07.
Article en En | MEDLINE | ID: mdl-29322601
The magnitude and direction of carbon cycle feedbacks under climate warming remain uncertain due to insufficient knowledge about the temperature sensitivities of soil microbial processes. Enzymatic rates could increase at higher temperatures, but this response could change over time if soil microbes adapt to warming. We used the Arrhenius relationship, biochemical transition state theory, and thermal physiology theory to predict the responses of extracellular enzyme Vmax and Km to temperature. Based on these concepts, we hypothesized that Vmax and Km would correlate positively with each other and show positive temperature sensitivities. For enzymes from warmer environments, we expected to find lower Vmax , Km , and Km temperature sensitivity but higher Vmax temperature sensitivity. We tested these hypotheses with isolates of the filamentous fungus Neurospora discreta collected from around the globe and with decomposing leaf litter from a warming experiment in Alaskan boreal forest. For Neurospora extracellular enzymes, Vmax Q10 ranged from 1.48 to 2.25, and Km Q10 ranged from 0.71 to 2.80. In agreement with theory, Vmax and Km were positively correlated for some enzymes, and Vmax declined under experimental warming in Alaskan litter. However, the temperature sensitivities of Vmax and Km did not vary as expected with warming. We also found no relationship between temperature sensitivity of Vmax or Km and mean annual temperature of the isolation site for Neurospora strains. Declining Vmax in the Alaskan warming treatment implies a short-term negative feedback to climate change, but the Neurospora results suggest that climate-driven changes in plant inputs and soil properties are important controls on enzyme kinetics in the long term. Our empirical data on enzyme Vmax , Km , and temperature sensitivities should be useful for parameterizing existing biogeochemical models, but they reveal a need to develop new theory on thermal adaptation mechanisms.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Microbiología del Suelo / Cambio Climático / Neurospora Tipo de estudio: Diagnostic_studies / Prognostic_studies Idioma: En Revista: Glob Chang Biol Año: 2018 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido
Texto completo
Añadir a Mi BVS
Imprimir
XML
PubMed Links
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Microbiología del Suelo / Cambio Climático / Neurospora Tipo de estudio: Diagnostic_studies / Prognostic_studies Idioma: En Revista: Glob Chang Biol Año: 2018 Tipo del documento: Article País de afiliación: Estados Unidos Pais de publicación: Reino Unido