Her protégés are just five to ten micrometres long and love being warm and cosy. Dr Sabine Kutschke is cultivating micro-organisms that will eventually be used to extract copper deposits from ore. She is one of the leading scientists in the Biotechnology research group at Helmholtz Institute Freiberg for Resource Technology (HIF). “Raw materials are becoming increasingly scarce, so we need to recover deposits that can’t be extracted using conventional mining methods,” says the 44-year-old researcher. Kutschke and her colleagues are investigating new ways of extracting metal which is very finely dispersed in rocks and chemically bound to sulphur. This is where the bacteria come into play. Solely using their metabolic process, certain micro-organisms can break down the copper sulphide compound and separate the copper from the sulphur. It is precisely these bacteria that Sabine Kutschke is nurturing so carefully.

Nature as a model of highly advanced technology

Sabine Kutschke reaches into a shaking incubator and takes out five Erlenmeyer flasks containing a grey liquid. “This is finely ground copper shale from the Lausitz region, mixed with bacteria in a nutrient solution,” she explains. At a sterile workstation, the researcher takes a sample from each flask and transfers it to a small test tube. She then examines the samples under a microscope. She finds what she is looking for in the third sample and points excitedly to an elongated blob on the screen – a greatly magnified bacterium. The combination of nutrient solution and heat has worked successfully in the third sample and the bacteria have multiplied. That is exactly what Sabine Kutschke wanted – to cultivate as many micro-organisms as possible. Billions of them are needed in order to leach the sought-after copper in large quantities from copper shale deposits.

From laboratory to industry: 100 millimetres to 100 cubic metres

In the HIF laboratory at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), this technique is already being successfully applied. Non-scientists can see the colour of the liquid in the test tube changing from grey to blue. “That’s because copper turns blue when it dissolves,” says Sabine Kutschke. The metal then needs to go through another stage of extraction to turn it into a reusable form of copper. This may involve electrolysis, for example, which produces copper particles by means of electrical energy. The use of bacteria in copper ore mining to extract the precious reddish brown metal helps to conserve resources and is an environmentally friendly process. It does not involve any chemical additives, such as sulphuric acid. “For me, it would be a real success if we were able to scale up from a 100-millilitre sample to a hundred cubic metres and run the whole process on an industrial scale,” explains Sabine Kutschke. It would then be possible to use this innovative process at many different copper deposit sites around the world.

Ecometals: a high-calibre international research project

An important step towards making this happen is the joint German-French “Ecometals” project launched in mid-April. Kutschke helped to raise funding for this major project, which involves 15 high-calibre research institutions and corporate partners. The project will run for three years and has received funding of EUR 4.2 million from the German Federal Ministry of Education and Research and EUR 1 million from the Agence Nationale de la Recherche, an institution dedicated to promoting science and research in France.