Catalytic power of enzymes decreases with temperature: New insights for understanding soil C cycling and microbial ecology under warming

作者：Gaël Alvarez, Tanvir Shahzad, Laurence Andanson, Michael Bahn, Matthew D. Wallenstein, Sébastien Fontaine · 发表于：Global Change Biology · 年份：2018 · DOI：10.1111/gcb.14281 · 被引用次数：107 · 研究领域：Biofuel production and bioconversion、Soil Carbon and Nitrogen Dynamics、Enzyme Catalysis and Immobilization

Abstract Most current models of soil C dynamics predict that climate warming will accelerate soil C mineralization, resulting in a long‐term CO 2 release and positive feedback to global warming. However, ecosystem warming experiments show that CO 2 loss from warmed soils declines to control levels within a few years. Here, we explore the temperature dependence of enzymatic conversion of polymerized soil organic C ( SOC ) into assimilable compounds, which is presumed the rate‐limiting step of SOC mineralization. Combining literature review, modelling and enzyme assays, we studied the effect of temperature on activity of enzymes considering their thermal inactivation and catalytic activity. We defined the catalytic power of enzymes ( E power ) as the cumulative amount of degraded substrate by one unit of enzyme until its complete inactivation. We show a universal pattern of enzyme's thermodynamic properties: activation energy of catalytic activity ( EA cat ) < activation energy of thermal inactivation ( EA inact ). By investing in stable enzymes (high EA inact ) having high catalytic activity (low EA cat ), microorganisms may maximize the E power of their enzymes. The counterpart of such EA s’ hierarchical pattern is the higher relative temperature sensitivity of enzyme inactivation than catalysis, resulting in a reduction in E power under warming. Our findings could explain the decrease with temperature in soil enzyme pools, microbial biomass ( MB ) and carbon use efficienc...