Autotrophic organisms can obtain nutrients and energy needed for their own life activities in the process of synthesizing organic matter from inorganic substances. Green plants, such as algae, mosses, ferns and seed plants, rely on their unique chloroplasts and use solar energy to synthesize organic substances from CO2 and water to feed themselves. Some chemically synthetic bacteria, such as nitrifying bacteria, sulfur bacteria, iron bacteria, etc. , can oxidize inorganic substances, using the energy released by oxidation to make the required nutrients.

That is, autotrophs, some can produce oxygen by themselves, and some are anaerobic. .