Greek autos - self, trophe - food
organisms producing organic matters from inorganic joints with the help of solar energy (phototrophes or heliotrophes) or energy released from chemical reactions of acidification of ammonia, hydrogen sulfide and other substances. Among A., there may be ranked the higher plants (with the exception of parasitic and saprophytic), algae, bacteria (purple, iron organisms, sulfide bacteria, etc.). In food chains they execute a role of producers. Compare: Heterotrophes.