From Discover:
When Michigan State University artist Adam Brown learned of a type of bacteria, Cupriavidus metallidurans, that can extract pure gold from the toxic solution gold chloride (a totally artificial salt), he hurried to an expert colleague, microbiologist Kazem Kashefi, with a question: “Is it possible to make enough gold to put in the palm of my hand?” Brown merely wanted to satisfy his intellectual and artistic curiosity, inspired by the gold-tinted roots of alchemy, the precursor of modern chemistry.
Soon thereafter, Kashefi and Brown set to work designing a half-experiment, half-art-exhibit that exposes C. metallidurans to gold chloride in a hydrogen-gas-rich atmosphere that serves as a source of food. Over the course of a week, the bacteria gradually strip-mined the toxic liquid, leaving flecks of pure 24-karat gold behind. The inefficient technique won’t supplant traditional mining, but the idea of using microbes as production facilities for a range of rare and difficult-to-produce materials has been gaining traction over the past several years.
More here.