The extraction of K(+) and SiO(2 )from silicate minerals by Bacillus mucilaginosus in liquid culture was studied in incubation experiments. B. mucilaginosus was found to dissolve soil minerals and mica and simultaneously release K(+) and SiO(2) from the crystal lattices. In contrast, the bacterium did not dissolve feldspar. B. mucilaginosus also produced organic acids and polysaccharides during growth. The polysaccharides strongly adsorbed the organic acids and attached to the surface of the mineral, resulting in an area of high concentration of organic acids near the mineral. The polysaccharides also adsorbed SiO(2) and this affected the equilibrium between the mineral and fluid phases and led to the reaction toward SiO(2 )and K(+) solubilization. These two processes led to the decomposition of silicate minerals by the bacterium.