Biosensors- and indicators


Microbial Exploration for gold, platinum and base metals in Australia

The on-going revolution in molecular biology offers the prospect of new tools for exploration under cover. Modern molecular techniques have enabled the generation of detailed profiles of microorganisms inhabiting different environments, and an understanding of the genetic pathways that enable organisms to survive (and thrive) in metal-rich environments and to exploit even the most unlikely micro-environments (for example, the surface of a gold grain embedded within the regolith). This leap in molecular-level understanding occurs concurrently with the rapid development of tools based on molecular genetics: the higher sensitivity and ever decreasing costs of these techniques make their routine application to the challenges of mineral exploration in the near future a certainty.

Two main methods hold great prospects. Bioindicators refer to differences in the microbial genes, species or community profiles expressed in areas overlying mineralisation compared to background regions. For example, the composition of microbial communities was linked to the presence of gold and its pathfinder elements. Microarrays, a state-of-the-art molecular technique enabling rapid analysis of thousands of genes, were used to show a correlation between the composition of microorganisms and metals around a base metal prospect.

Another possible application of molecular technology for use in gold exploration are biosensors. Biosensors are analytical devices that are based on biological components and are developed to detect specific compounds: the most famous example of a biosensor is the blood glucose monitor. The use of biosensing technologies over traditional techniques for mineral exploration holds value in the speed, portability and high selectivity of these devices. The development of biosensors for gold exploration will mean that exploration teams will be able to obtain gold concentrations from an environmental sample immediately. In addition, biosensing devices may also aid in mineral processing where real-time in-line analysis of specific mineral components of ores could be determined, enabling real-time fine-tuning of the process to improve recovery and costs. Using molecular techniques, such as transcriptomics, genes from Cupriavidus metallidurans CH34 and Salmonella typhimurium have been identified and are now being investigated for their use as a gold biosensor.