Micro-biophysical interactions at bacterium-mineral interfaces determine potassium dissolution

Bacteria-mineral interactions are widespread in the Earth's critical zones. They play essential roles in soil ecosystems, e.g., minerals weathering, soil formation, soil nutrient cycling and climate change. Employing a microscopy experimental system, we quantified how microscale interactions between Pseudomonas aeruginosa PAO1 and potassium feldspar influence mineral dissolution and potassium bioavailability. The results revealed that P. aeruginosa PAO1 tended to adhere onto the mineral solid-liquid interfaces facilitated by the bacterial flagellar- and pilusmediated interfacial motilities, which are often highly hindered by the mineral rough interfaces typically under hydration stress circumstances. The surface-attached bacterial life-form likely intensified potassium feldspar dissolution and thereby enhanced potassium releasing. As a consequence, it promoted bacterial population proliferation which further reinforced localized interactions between P. aeruginosa PAO1 and minerals, accelerating potassium release. In addition, the bacterial biofilm formation and potassium release peaked at 30 h after incubation, with a maximum available potassium concentration of 19.96 mg l - 1 and a ratio of public potassium contribution of 47.0%. These cell-scale quantitative estimates on bacteria-minerals interactions provide new insights into mechanistic understanding of microbial functionalities in regulating the biogeochemical processes of soil elements.