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ZIWR Weekly Seminar

Wednesday, June 9, at 13:15

live in classroom 1 of the AKIS building and also via zoom at   https://us02web.zoom.us/j/85701060624

​"Resuscitation of arid soil communities during hydration-desiccation cycles"

Capucine Baubin

PhD candidate in Soil Microbial Ecology

Ben-Gurion University of the Negev, Israel

In desert ecosystems, temporal dynamics are separated by hydration and desiccation cycles. For copiotrophs, organisms thriving in nutrients-rich environments, this means that they are either hydrated and active or desiccated and inactive. For oligotrophs, organisms surviving in nutrients-poor environments, this means that they will function best in times of low nutrient concentrations. The main aim of this study was to determine the fate of soil microbial communities before and during their passage between phases (desiccation and hydration). To achieve this aim, we explored different aspects of desert rain events: First, we looked at the changes in the microbial communities with increasing aridity levels, using shallow shotgun metagenomics. This showed that each aridity level supports unique protist taxa and that there are changes in the functions of the communities based on the water level in the environment. Second, we studied the changes in the bacterial communities in the biological soil crust (BSC). We noticed that dry and wet communities are dominated by different phyla and that, while the water content decreases fast after a rain event, the activity level stays high owing to the secreted extracellular polymeric substances. Third, we checked the production of petrichor (“the smell of rain") in the soil and tried to link its emission to the microbial community. We understood that components of the petrichor (geosmin and 2-methylisoborneol) are actively produced right after the rain event, and that their production is tightly regulated. The results obtained from these three projects, suggest that arid soil community dynamics are ruled by hydration-desiccation cycles, and that the petrichor plays a key role in the response of the community to hydration. Yet, the petrichor-mediated interactions need to be researched further.