<P> They can catabolize organic compounds by respiration, fermentation, or both . Fermenting heterotrophs are either facultative or obligate anaerobes that carry out fermentation in low oxygen environments, in which the production of ATP is commonly coupled with substrate - level phosphorylation and the production of end products (e.g. alcohol, CO2, sulfide). These products can then serve as the substrates for other bacteria in the anaerobic digest, and be converted into CO and CH, which is an important step for the carbon cycle for removing organic fermentation products from anaerobic environments . Heterotrophs can undergo respiration, in which ATP production is coupled with oxidative phosphorylation . This leads to the release of oxidized carbon wastes such as CO and reduced wastes like H O, H S, or N O into the atmosphere . Heterotrophic microbes' respiration and fermentation account for a large portion of the release of CO into the atmosphere, making it available for autotrophs as a source of nutrient and plants as a cellulose synthesis substrate . </P> <P> Respiration in heterotrophs is often accompanied by mineralization, the process of converting organic compounds to inorganic forms . When the organic nutrient source taken in by the heterotroph contains essential elements such as N, S, P in addition to C, H, and O, they are often removed first to proceed with the oxidation of organic nutrient and production of ATP via respiration . S and N in organic carbon source are transformed into H S and NH through desulfurylation and deamination, respectively . Heterotrophs also allow for dephosphorylation as part of decomposition . The conversion of N and S from organic form to inorganic form is a critical part of the nitrogen and sulfur cycle . H S formed from desulfurylation is further oxidized by lithotrophs and phototrophs while NH formed from deamination is further oxidized by lithotrophs to the forms available to plants . Heterotrophs' ability to mineralize essential elements is critical to plant survival . </P> <P> Most opisthokonts and prokaryotes are heterotrophic; in particular, all animals and fungi are heterotrophs . Some animals, such as corals, form symbiotic relationships with autotrophs and obtain organic carbon in this way . Furthermore, some parasitic plants have also turned fully or partially heterotrophic, while carnivorous plants consume animals to augment their nitrogen supply while remaining autotrophic . </P> <P> Animals are heterotrophs by ingestion, fungi are heterotrophs by absorption . </P>

What is the importance of heterotrophs in an ecosystem