Climate Extremes and the Soil Microbiome.

Earth System climate models predict an intensification of precipitation patterns.  These changes can impact the global and regional hydrologic cycle resulting in weather extremes such as droughts or high intensity rainfall events. As soil microorganisms are the key regulators of biogeochemical processes, their response to extreme wetting or drying events is a significant factor in predicting ecosystem processes. Perturbations like extreme wetting or drying of soil expose organic matter protected in the soil matrix to microbial degradation leading to increased carbon dioxide (CO₂) and methane production.  Delineation of life strategies as a framework for predicting responses of microbial communities to perturbations have been proposed. Constitutive physiological adaptations to moisture pulses require large investment of resources; we therefore, hypothesize that extreme moisture regimes will select for microbial taxa with life-history strategies adapted to desiccation or moisture stress. We tested this hypothesis by subjecting three Kansas native prairie soils to air-drying and water saturation for 15 days at 21 ^oC. A control treatment was similarly maintained. All incubations were performed in triplicates in a randomized block design resulting in a total of 27 samples. DNA and RNA were extracted from each treatment replicate (0.25 g soil). We will measure community level responses by 16S rRNA gene sequencing achieved by amplifying the V4 region. gDNA libraries were prepared for sequencing on the Illumina MiSeq platform using the V3 chemistry (Illumina) for metagenomics. cDNA was synthesized and sequenced similarly for metatranscriptomics. Metagenomics will allow a deeper understanding of the soil microbial diversity and to identify the “players” that are potentially involved in functioning of the system. Since research in the field of soil metatranscriptomics is in its early stages, this work will significantly advance the field in applications of multi-omic tools to uncover the functional adaptations of soil microbial communities to local environmental conditions.