energyautotrophic

Energyautotrophic is a nonstandard term sometimes used to describe organisms that synthesize organic matter using energy derived from inorganic reactions and carbon fixed from carbon dioxide. In most biological usage, these organisms are classified as autotrophs, and they are further categorized by their energy source: photoautotrophs rely on light, and chemoautotrophs rely on the oxidation of inorganic or reduced compounds.

Photoautotrophs, including plants, algae, and cyanobacteria, capture light energy with pigments and convert it into chemical energy through photosynthesis, fixing CO2 into sugars via pathways such as the Calvin cycle.

Chemoautotrophs obtain energy by oxidizing inorganic compounds such as hydrogen sulfide, ammonia, nitrite, iron, or methane. They fix CO2 using this chemical energy; common examples include nitrifying bacteria, sulfur-oxidizing bacteria, and hydrogen-oxidizing bacteria. These organisms often inhabit environments lacking light, such as deep-sea hydrothermal vents, soils, and sediments.

Because energyautotrophic organisms use inorganic energy sources, they act as primary producers in many ecosystems, converting inorganic carbon into organic matter that supports higher trophic levels. They are distinct from heterotrophs, which obtain carbon from preformed organic matter, and from mixotrophs, which combine autotrophic and heterotrophic nutrition.