Resumen de Rapid Shifts in Bacterial Community Assembly under Static and Dynamic Hydration Conditions in Porous Media

Hannah Kleyer, Robin Tecon, Dani Or

• The composition and activity of soil bacteria are central to various ecosystem services and soil biogeochemical cycles. A key factor for soil bacterial activity is soil hydration, which is in a constant state of change due to rainfall, drainage, plant water uptake, and evaporation. These dynamic changes in soil hydration state affect the structure and function of soil bacterial communities in complex ways often unobservable in natural soil. We designed an experimental system that retains the salient features of hydrated soil yet enables systematic evaluation of changes in a representative bacterial community in response to cycles of wetting and drying. The study shows that hydration cycles affect community abundance, yet most changes in composition occur with the less-abundant species (while the successful ones remain dominant). This research offers a new path for an improved understanding of bacterial community assembly in natural environments, including bacterial growth, maintenance, and death, with a special focus on the role of hydrological factors.