Fungi play important geoactive roles in the biosphere, particularly element biotransformations and biogeochemical cycling, metal and mineral transformations, decomposition, bioweathering, and soil and sediment formation. Fungi can apply various mechanisms to effect changes in metal speciation, toxicity and mobility, mineral formation and/or mineral dissolution. This research has examined fungal roles in bioweathering and bioleaching of zinc sulfide ore, together with an investigation of the role of fungal phosphatases in the bioprecipitation of uranium and lead when utilising an organic phosphorus-containing substrate as the sole phosphorus source. The results obtained revealed that test fungal species showed bioweathering effects on zinc sulfide ore, and clear evidence of biotransformation and bioleaching of zinc sulfide was obtained after growth of A. niger. The formation of zinc oxalate dihydrate resulted from oxalic acid excretion. The formation of uranium- and lead-containing biominerals after growth of yeasts and filamentous fungi with organic phosphorus sources have also been demonstrated and characterized. Test fungi were capable of precipitating uranium phosphate and pyromorphite, and also produced mycogenic lead oxalate during this process. This work is the first demonstration that filamentous fungi are capable of precipitating a variety of uranium- and lead-containing phosphate biominerals when grown with an organic phosphorus source. The role of fungal processes in the bioweathing and bioleaching of mineral ores, and the significance of phosphatases in the formation of uranium and lead secondary minerals has thrown further light on potential fungal roles in metal and mineral biogeochemistry as well as the possible significance of these mechanisms for element biorecovery or bioremediation.
|Date of Award||2015|
|Sponsors||British Mycological Society, Leng Charitable Trust & International Society for Environmental Biogeochemistry |
|Supervisor||Geoffrey Michael Gadd (Supervisor)|