Copper has been prized for keeping water clean since antiquity. But at least one bacterium is positively electric about copper.
Copper is an excellent conductor of heat and electricity. Copper is a rare “native” metal: one of the few metals that naturally occurs in a directly usable form.
Ancient civilizations exploited the antimicrobial properties of copper long before the littlest ones were discovered in the 19th century. Drinking water stayed fresher when piped through copper or kept in copper vessels. Ship hulls were clad in copper for centuries because such hulls resisted slime accumulation.
Copper is essential to all animals in minute amounts. But almost all microbes, including viruses, bacteria, and fungi, shun copper because of its specific reactivity. The bacterium Geobacter sulfurreducens is a notable exception.
G. sulfurreducens oxidizes metal ions and sips electrons as part of its diet. G. sulfurreducens is known as an electricigen for their ability to generate electricity and create an electric current.
G. sulfurreducens happily settle on copper, where they promote chemical reactions between the sulfate ions in their food and their copper home to generate electricity. The bacteria form biofilms and pipe electrons through copper sulfide wires they string throughout the colony, forming a food distribution system. G. sulfurreducens really know how to go with the flow.
References:
Laura Beuth et al, “Copper-bottomed: electrochemically active bacteria exploit conductive sulphide networks for enhanced electrogeneity,” Energy & Environmental Science (13 August 2020).
“Microbes with mettle build their own electrical ‘wires’,” Nature (27 August 2020).