Metabolic Response to Drought in Phylogenetically Similar Species

Microbes possess an array of traits that support their survival under constant fluctuating chemical conditions within soil pores. For example, a decline in the soil water potential under drought can provoke a metabolic response in a number of different organisms, including through the production and accumulation of non-structural carbohydrates and metabolites maintaining turgor and protecting the cellular structure. Changes in microbial metabolism in turn can feedback onto metabolite exudation, the chemical structure of necromass, and the formation of SOM. We examined the impact of imposing an osmotic or matric stress (as a proxy for drought) on microbial physiology using non-destructive synchrotron radiation-based Fourier transform IR (SR-FTIR) spectromicroscopy. Phylogenetically similar species of gram-positive and gram-negative microbes were isolated from soils with contrasting climate histories and were subjected to the different stresses. Through this, we were able to examine how short-term perturbations imparted different responses in gram-negative and gram-positive species, and to what extent the role climate history plays in the response to hydrological perturbations. This contribution will discuss the specific physiological changes under matric stress and the more acute osmotic stress, and potential for microbial adaptation to fluctuating environments.