Aknockout mouse is a mouse that has specific genes mutated (“knocked out”) so that the lack of production of the gene product can be studied in an animal model. Knockout mice are frequently used in pharmaceutical studies to test the potential for a particular human enzyme as a therapy target. Mice have identical or nearly identical copies of human proteins, making them useful in studies that model effects in humans.

Bioremediation is the use of organisms to remove toxic materials from the environment. Bacteria, protists, and fungi are good at degrading complex molecules into waste products that are generally safe and recyclable. Sewage treatment plants perform biore-mediation in a limited way. An example of bioremediation is the massive cleanup in Alaska following the Exxon Valdez oil spill in 1989. The superficial layer of oil was removed by suction and filtration, but the oil-soaked beach was cleaned by bacteria that could use oil as an energy source.