University of Dundee

Biophysical and biochemical characterization of fungal biominerals

Biomineralization refers to the collective processes by which organisms form minerals. For microbes, most examples of biologically-induced biomineralization result from activities of the organisms themselves, such as redox transformations of metals, sorption phenomena, and metabolic activities where metabolites, e.g. oxalate, respiratory CO2, and sulfide, precipitate metals in the cellular microenvironment. Because of their small particle size and reactive functional groups, biominerals have catalytic and other properties in nanoparticle, crystalline and colloidal forms. These include dramatic properties of sorption and nucleation of other ions and chemicals, redox catalysis, and antimicrobial effects. These potent qualities are directly relevant to development of novel bioengineered materials for structural, technological, environmental and other purposes. Fungi are increasingly recognised as major geoactive agents. Their natural roles are intimately associated with metal-and mineral transformations, including biomineralization, and the branching growth form can provide a manipulatable template for biomineral production. Biominerals and biometal(loid)s can be obtained in crystalline, colloidal, nano- and microparticulate forms, as pure preparations or in association with biomass.

 

There is growing interest in the nature and properties of biominerals, as well as the application of microbial bioprocessing approaches for recovery of metals and other elements from industrial leachates or process streams within environmental biotechnology. This is because most traditional physical and chemical methods for metal recovery are highly energy-intensive and bioprocessing is seen as an attractive energetically-economical approach. Biomineralization is clearly one approach that results in element removal from solution, and fungi are particularly amenable to growth in bioreactors where their metabolic properties could be exploited for this purpose. However, research is extremely limited in this relatively new field, and there has been little that seeks to explore the potential of fungal systems in biomineral formation, or indeed thoroughly characterise novel mycogenic biominerals to take these findings into new areas of understanding and exploitation. Such biominerals may also be formed from rare valuable elements that have received, as yet, scant research attention in environmental biotechnology.

 

Biomineralization by fungi is the theme of this interdisciplinary research project with the main objectives being to:

(a) use geoactive fungal strains to produce novel biominerals in colloidal, microparticulate and biomass-associated forms, including those derived from rare metallic and metalloid elements

(b) to characterise physico-chemical and biological properties of biominerals and biometal(loid)s using state-of-the-art particle manipulation technology as well as bulk phase approaches. (These approaches will be developed by the 2nd Supervisor, Dr McGloin, from physics and will also allow further development of collaboration with Dr Robert Thomson at Heriot-Watt University to produce laser written microfluidic chips with integrated optical traps, with a view to producing powerful new biomineralization analysis devices).

(c)  to assess purified biomineral/biometal(loid)s, or biomass-biomineral composites, for key properties in the context of impact and application in novel industrial biotechnology.