New hypotheses and old questions about soil community adaptations to water deficit
Water dynamics (drying and rewetting) physiologically demanding to organisms and cause well-known impacts on ecosystem energy and nutrient cycles. Most known mechanisms of microbial response to water dynamics have been derived from studies in laboratory culture, where microbes are relatively unstressed compared to environmental conditions. This is particularly true with regard to available C and nutrients. Sugars and amino acids and other metabolites have been measured across a range of habitats to determine how C and N availability and drying intensity affect microbial intracellular pools (Osmolyte Accumulation Hypothesis (OAH) thought to be involved in microbial adaptation to water deficit.
Data in support and refuting the OAH hypothesis in soil experiments will be presented. Variations in exopolysaccharides were also monitored to understand their role in microbial drought responses. The current thinking of these phenomenon for microbes and plant-microbial interactions will be described, with a bias toward my own thoughts and logic regarding microbial adaptation to soil desiccation.