University of Dundee

Geomicrobiology and Geomycology - Metal and Mineral Transformations by Fungi

Microorganisms are intimately involved in geological processes and metal and mineral transformations have a central place in such phenomena as bioweathering, element cycling, mineral dissolution and mineral formation. The balance between metal mobilization and immobilization varies depending on the organisms involved, their environment and physico-chemical conditions. For metal (and metal radionuclide) contaminants, mobilization can arise from leaching mechanisms, and complexation by metabolites. Immobilization can result from sorption, transport and intracellular sequestration or precipitation as organic and inorganic compounds. Although prokaryotes (bacteria and archaea) dominate microbial communities under anaerobic conditions, fungi are ubiquitous in aerobic soils and often dominate the microbiota in low pH and metal-polluted systems. Fungal importance in geochemical activities has often been underestimated. In terrestrial environments, fungi promote rock weathering and contribute to the dissolution of mineral aggregates in soil through excretion of H+, organic acids and other ligands, or through redox transformations of mineral constituents. Fungi also play an active or passive role in mineral formation through precipitation of secondary minerals, e.g. oxalates, oxides, carbonates and phosphates and through the nucleation of crystalline material onto cell walls. Such interactions between fungi and minerals are of importance to biogeochemical cycles including those of C, N, S and P, as well as being of relevance to bioremediation approaches for contaminated soil.

This PhD project area seeks to assess and characterize key fungal processes which affect the bioavailability of metals in the terrestrial environment, particularly mineral dissolution and mineral formation. The research employs a range of chemical, biochemical and molecular techniques. In addition, the project will provide training in methodologies and approaches of direct relevance to bioremediation and environmental management.

Applications are invited from graduates who possess a good Honours degree (2.1 or above) in microbiology, environmental chemistry, or other relevant discipline to work in a multi-disciplinary and internationally-acclaimed research environment. Experience of molecular methods in microbiology, mineralogy and biological chemistry would be advantageous. Applications are especially welcomed from overseas candidates who have their own scholarship or funding sources.

References

  1. Wei, Z., Liang, X., Pendlowski, H., Hillier, S., Suntornvongsagul, K., Sihanonth, P. and Gadd, G.M. (2013) Fungal biotransformation of zinc silicate and sulfide mineral ores. Environmental Microbiology (in press) DOI: 10.1111/1462-2920.12089.
  2. Kangwankraiphaisan, T., Suntornvongsagul, K., Sihanonth, P., Klysubun, W. and Gadd, G.M. (2013).  Influence of arbuscular mycorrhizal fungi (AMF) on zinc biogeochemistry in the rhizosphere of Lindenbergia philippensis growing in zinc-contaminated sediment. Biometals 26, 489–505.
  3. Pinzari, F., Tate, J., Bicchieri, M.,  Rhee, Y.J., and Gadd, G.M. (2013) Biodegradation of ivory (natural apatite): possible involvement of fungal activity in biodeterioration of the Lewis Chessmen. Environmental Microbiology 15, 1050–1062.
  4. Rhee, Y.J., Hillier, S., and Gadd, G.M. (2012). Lead transformation to pyromorphite by fungi. Current Biology 22, 237-241.
  5. Wei, Z., Hillier, S. and  Gadd, G.M. (2012). Biotransformation of manganese oxides by fungi: solubilization and production of manganese oxalate biominerals. Environmental Microbiology 14, 1744-1753.
  6. Gadd, G.M. (2010). Metals, minerals and microbes: geomicrobiology and bioremediation (Colworth Prize Lecture). Microbiology 156, 609 – 643.
  7. Gadd, G.M. and Raven, J.A. (2010). Geomicrobiology of eukaryotic microorganisms. Geomicrobiology Journal 27, 491-519.
  8. Fomina, M., Burford, E.P., Hillier, S., Kierans, M. and Gadd, G.M. (2010). Rock-building fungi. Geomicrobiology Journal 27, 624-629.
  9. Fomina, M., Charnock, J.M., Hillier, S., Alvarez, R., Francis Livens, F. and Gadd, G.M.  (2008). Role of fungi in the biogeochemical fate of depleted uranium. Current Biology  18, 375-377.