Persistence of microbial extracellular enzymes in soils under different temperatures and water availabilities

• Published in: Ecology and evolution 2020-09, Vol.10 (18), p.10167-10176
• Main Authors: Gómez, Enrique J., Delgado, Jose A., González, Juan M.
• Format: Article
• Language: English
• Subjects: Climate change; Complexity; Enzymatic activity; Enzyme activity; Enzymes; extracellular enzyme activity; Extracellular enzymes; Heterogeneity; High temperature; Loam soils; Microbial activity; Microorganisms; Mineralization; Organic matter; organic matter decomposition; Organic soils; Original Research; persistence; Soil conditions; Soil environment; Soil microorganisms; Soil organic matter; Soil temperature; Soils; temperature; Thermophiles; water activity; Water availability
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.6677

Microbial extracellular enzyme activity (EEA) is critical for the decomposition of organic matter in soils. Generally, EEA represents the limiting step governing soil organic matter mineralization. The high complexity of soil microbial communities and the heterogeneity of soils suggest potentially complex interactions between microorganisms (and their extracellular enzymes), organic matter, and physicochemical factors. Previous studies have reported the existence of maximum soil EEA at high temperatures although microorganisms thriving at high temperature represent a minority of soil microbial communities. To solve this paradox, we attempt to evaluate if soil extracellular enzymes from thermophiles could accumulate in soils. Methodology at this respect is scarce and an adapted protocol is proposed. Herein, the approach is to analyze the persistence of soil microbial extracellular enzymes at different temperatures and under a broad range of water availability. Results suggest that soil high‐temperature EEA presented longer persistence than enzymes with optimum activity at moderate temperature. Water availability influenced enzyme persistence, generally preserving for longer time the extracellular enzymes. These results suggest that high‐temperature extracellular enzymes could be naturally accumulated in soils. Thus, soils could contain a reservoir of enzymes allowing a quick response by soil microorganisms to changing conditions. This study suggests the existence of novel mechanisms of interaction among microorganisms, their enzymes and the soil environment with relevance at local and global levels. Soil microbial extracellular enzyme activity is highest at high temperature even if thermophiles represent a minimum fraction of the total bacterial community. We study the persistence of mesophilic and thermophilic enzymes in soils in relationship to temperature and water content. Enzymes active at high temperature (i.e., 60°C) last longer time than those from mesophiles. High‐temperature extracellular enzymes can accumulate in soils which explains the high extracellular enzyme activity at high temperatures observed in soils. This study contributes to better understand microbe‐organic matter interactions in soils and predicts a significant influence of global warming on soil microbial extracellular enzyme activity.