Uranium waste bacteria. Coloured scanning electron micrograph (SEM) of Geobacter metallireducens bacteria (green) being used to digest uranium waste. This bacteria is able to survive in radioactive environments and turn the uranium waste from a soluble form (that can contaminate water supplies) to a solid form. Other species of Geobacter bacteria can eliminate petroleum contamination in polluted water and convert waste organic matter to electricity. Geobacter sp. are anaerobic bacteria (living without oxygen) that use metals to gain energy in the same way that humans use oxygen. Magnification: x2880 at 10 centimetres wide.