Cyanobacteria, including that monumentally abundant Prochlorococcus, convert light to energy and deliver, as byproduct, a large share of Earth’s free atmospheric oxygen. Purple bacteria photosynthesize too, but do it by drawing upon sulfur or hydrogen instead of water as fuel for the process, and they don’t produce oxygen. Lithotrophic bacteria, the rock eaters, deriving their energy from iron, sulfur, and other inorganic compounds, exist in more ingenious variants than you care to know. Japanese researchers have recently discovered a new bacterium, Ideonella sakaiensis, that digests plastic.
