Latitude-dependent underestimation of microbial extracellular enzyme activity in soils

Abstract

Decomposition of soil organic matter by microorganisms is a major process governing the carbon balance between soil and atmosphere which needs to be fully understood. Extracellular enzyme activity is often the limiting factor for microbial utilization of soil organic matter. Contrary to expectations, we observed that enzymatic activity rises at increasing temperatures in soils and sediments. Current climatic change will induce the increase of global mean temperatures, frequency of extreme heat events and soil temperatures during the next decades. The relevance of the increase in activity at high temperature is dependent on latitude. At latitudes around and below 40° a significant number of days per year present high temperatures. Results suggest that the hydrolytic activity of microbial extracellular enzymes is currently underestimated mainly at medium and low latitudes where soil temperatures frequently reach high values (often above 40 °C). This report contributes to understand (1) the hydrolysis of soil organic matter within a latitude-dependent scenario of global warming and (2) the role of microorganisms in processing soil organic matter and their influence in carbon cycling.