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USING MICROBES TO MINE METALS AND CLEAN UP SPOIL
Mineral loving microbes are used to mine metals and could be used to clear up corrosive acid pollution left over from industrial workings, say Welsh scientists speaking at the Society for General Microbiology's 156th Meeting at Heriot-Watt University, Edinburgh. Mankind has been using metals for thousands of years, and we even name key stages of our civilisation such as the Iron Age and Bronze Age after them. But micro-organisms have been using metals for millions of years, as food, as energy sources, and instead of oxygen to breathe. Mining ore bodies to get at coal, iron and other metals gives the micro-organisms access to a wide range of minerals, especially sulphur compounds such as fools gold (or iron pyrites), which are also found below the surface, and which we discard in our spoil heaps or expose in our mineshafts and run off in waste water. "This is not good news," says Dr Barrie Johnson from the University of Wales, Bangor, "as the bacteria which thrive under these conditions generate acidic metal-rich effluents which pollute many streams and rivers in the UK and elsewhere." However the scientists have developed ways to harness these mineral degrading microbes as biominers, to extract gold, copper, cobalt and other metals from their ores without the costs of smelting, the huge energy needs, or the atmospheric pollution. These should greatly reduce the costs and environmental impact of mining in the future. Abandoned mines, spoil heaps and tailings are increasingly posing a serious environmental hazard, and there have been some major pollution incidents at mining sites such as at Wheal Jane in Cornwall in January 1992, Aznalcóllar in Spain in April 1998, and Baia Mare in Romania in January 2000. "Our ongoing research is focussing on extending the applications of biomining technology, and on using newly discovered extremophile bacteria to simultaneously recover metals and clean up mine effluents from abandoned mines, streams that pass through them and their waste tips," says Dr Johnson.
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