chemosynthesis

Method of making protoplasm (contents of a cell) using the energy from chemical reactions, in contrast to the use of light energy employed for the same purpose in photosynthesis. The process is used by certain bacteria, which can synthesize organic compounds from carbon dioxide and water using the energy from special methods of respiration.

Nitrifying bacteria are a group of chemosynthetic organisms that change free nitrogen into a form that can be taken up by plants; nitrobacteria, for example, oxidize nitrites to nitrates. This is a vital part of the nitrogen cycle. As chemosynthetic bacteria can survive without light energy, they can live in dark and inhospitable regions, including the hydrothermal vents of the Pacific Ocean. Around these vents, where temperatures reach up to 350°C/662°F, the chemosynthetic bacteria that can use the oxidation of sulphides as an energy source are the basis of a food web supporting fishes and other marine life.