Metal and mineral transformations by microorganisms

Microorganisms are intimately involved in soil processes that affect contaminant bioavailability. 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. However, there is a lack of detailed information on the relative importance of these processes in terrestrial systems, the nature of the communities involved, or their significance both in engineered soil remediation solutions and in natural attenuation of contaminated sites. An understanding of microbial determination of metal bioavailability is essential for any attempts at remediation. 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. Fungi often have the largest biomass of all organisms present while their symbiotic association (mycorrhiza) with over 80% of terrestrial plant species has profound consequences for geochemical processes in the soil and root environment. However, 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, and through the nucleation of crystalline material onto cell walls that can result in the formation of biogenic micro-fabrics within mineral substrates. Such interactions between fungi and minerals are of importance to biogeochemical cycles including those of C, N, S and P.

This PhD project therefore seeks to assess and characterize key fungal processes which affect the bioavailability of metals in the terrestrial environment, and will employ 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 biology, or other relevant discipline to work in an active multi-disciplinary and internationally-acclaimed research environment. Experience of molecular methods in microbiology and biological chemistry would be advantageous. Only UK residents are eligible for this research-council funded position.

Informal enquiries may be made to Professor G.M. Gadd ([Email Address Removed]): further information on the Division is found at http://www.lifesci.dundee.ac.uk/mmb .