The Release of Metallic and Silicate Ions From Minerals, Rocks, and Soils by Fungal Activity

Summary The decomposition of silicate minerals and related substances by fungi has been investigated using two techniques: (a) the incorporation of the mineral material in agar medium, when its breakdown is indicated by the formation of clear zones round the fungal growth; (b) the determination of the metal and silicate ions, derived from the insoluble materials and brought into solution as a result of fungal activity in liquid medium. Strains of fungi which produced citric and/or oxalic acid proved to be effective in decomposing certain natural silicates, while an oxalic acid‐producing strain also released metallic ions and silica from rocks and soils. A possible role of fungi in biological weathering is discussed.