Biofilms reshape soil-water dynamics with enhanced vapor adsorption and hysteresis reversal under dry conditions

< 0.6), where biofilm-dominated adsorption exceeds particle surface desorption. Mechanistic analysis demonstrates that EPS components influence SWVS through functional groups (-COOH and -OH) with strong water-binding affinity, EPS swelling, and suppression of cation/surface hydration, which physically obscures localized mineral surfaces. A conceptual framework for vapor dynamics in biofilm-colonized soils is proposed, and such results address a gap in understanding biological controls on soil hydrology under drought.