Response of Microbial Communities and Their Metabolic Functions to Drying⁻Rewetting Stress in a Temperate Forest Soil.

Sophie Zechmeister-Boltenstern,Uwe Wegner,Dong Liu,Christian Lassek,Michael Zimmermann,Katharina M. Keiblinger,Sonja Leitner,Stephan Fuchs,Katharina Riedel

doi:10.3390/microorganisms7050129

Abstract

Global climate change is predicted to alter drought–precipitation patterns, which will likely affect soil microbial communities and their functions, ultimately shifting microbially-mediated biogeochemical cycles. The present study aims to investigate the simultaneous variation of microbial community compositions and functions in response to drought and following rewetting events, using a soil metaproteomics approach. For this, an established field experiment located in an Austrian forest with two levels (moderate and severe stress) of precipitation manipulation was evaluated. The results showed that fungi were more strongly influenced by drying and rewetting (DRW) than bacteria, and that there was a drastic shift in the fungal community towards a more Ascomycota-dominated community. In terms of functional responses, a larger number of proteins and a higher functional diversity were observed in both moderate and severe DRW treatments compared to the control. Furthermore, in both DRW treatments a rise in proteins assigned to “translation, ribosomal structure, and biogenesis” and “protein synthesis” suggests a boost in microbial cell growth after rewetting. We also found that the changes within intracellular functions were associated to specific phyla, indicating that responses of microbial communities to DRW primarily shifted microbial functions. Microbial communities seem to respond to different levels of DRW stress by changing their functional potential, which may feed back to biogeochemical cycles.

Highlights

In the upcoming decades, the frequency and intensity of extreme climatic events, like severe droughts and heavy rainfalls, will likely increase in many forested regions of the world [1] due to global climate change [2]
The results showed that fungi were more strongly influenced by drying and rewetting (DRW) than bacteria, and that there was a drastic shift in the fungal community towards a more Ascomycota-dominated community
Here we found no significant effect of DRW stress on soil N and P, which can likely be attributed to the fact that these nutrients were measured in soil extracts which have been shown to introduce a number of biases [39,40,41], which have likely masked any effects of drying and rewetting on soil nutrient availability in our study

Summary

Introduction

The frequency and intensity of extreme climatic events, like severe droughts and heavy rainfalls, will likely increase in many forested regions of the world [1] due to global climate change [2]. Extracellular enzymes continue hydrolyzing and oxidizing organic matter well after microbial activity has slowed down, leading to an accumulation of -available C and N that is not immobilized by microorganisms or plant roots [12] Upon rewetting, this labile C and N is mobilized [13] and triggers a boost in microbial activity and growth, leading to elevated respiration and soil CO2 emissions, even days or weeks after the rewetting event [8,11,14]. Due to differences in stress resistance and resilience between different microbial taxa, frequent DRW events and the associated (rapid) changes in soil moisture and substrate availability can trigger microbial population changes that likely translate into functional changes Concerning their life strategy, microbes can be classified as either copiotrophic (fast growing, less stress resistant) or oligotrophic (slow growing, more stress resistant). Oligotrophic microorganisms with a slower cell growth are usually more resistant to drought because they have more stable cell walls [19]

Methods

Results

Conclusion