TRANSFORMATIONS AND BIOWEATHERING OF METALS AND MINERALS BY FREE-LIVING AND SYMBIOTIC FUNGI

“Geomicrobiology” can be defined as the impact of microbes on geological processes, and includes weathering of rocks and minerals, transformations of metals and related substances, and biogeochemical cycling of the elements. Weathering activities of microbes, both biophysical and biochemical, affect rock and mineral structure and composition which in turn leads to alterations in the speciation of metals and other mineral components. Microorganisms are intimately involved in metal biogeochemistry whether arising from natural environmental sources or anthropogenic activity. “Geomycology” can be considered a subset of “geomicrobiology” and defined as the impact of fungi on geological processes. Although the main focus of geomicrobiology is on prokaryotes, it is clear that fungi comprise a significant component of the microbiota in a range of rocks and mineral-based substrata. Furthermore, a remarkable adaptation of fungi for exploitation of the terrestrial environment is their ability to form symbiotic partnerships with plants (mycorrhizas) and algae or cyanobacteria (lichens). Lichens are fungi that exist in symbiosis with one or more photosynthesizing partners, and play an important role in many biogeochemical processes. Nearly all land plants appear to depend on mycorrhizal fungi and these are involved in metal mobilization from minerals, metal immobilization within biomass, and extracellular precipitation of mycogenic biominerals. Our research seeks to understand mechanisms of metal and mineral biotransformations, and their environmental and applied significance in bioremediation and biodeterioration. This presentation will include examples of research on fungi inhabiting certain rock types, soil, including the mycorrhizosphere, in relation to mineral dissolution and transformation, and the formation of secondary mycogenic minerals.

Gadd GM. 2007. Geomycology: biogeochemical transformations of rocks, minerals, metals and radionuclides by fungi, bioweathering and bioremediation. Mycol Res 111: 3-49.

Gadd, G.M. 2010. Metals, minerals and microbes: geomicrobiology and bioremediation. Microbiol 156: 609 – 643.