Syntrophy

Syntrophy is the phenomenon that one species lives off the products of another species.

House dust mites, for instance, live off of human skin flakes, of which a healthy human being produces about 1 gram per day. A less pleasant property of these mites is that they can produce compounds that stimulate the production of skin flakes, and people can become allergic to these compounds.

Another example the many organisms that feast on faeces or dung. A cow eats a lot of grass, the cellulose of which is transformed into lipids by micro-organisms in the gut of the cow. These micro-organisms can't use the lipids because of lack of dioxygen in the gut, so the cow does not take up all lipids produced. When the processed grass leaves the gut as faeces and comes into open air, many organisms, such as the dung beetle, feast on the dung.

Yet another example is the community of micro-organisms in soil that live off of leaf litter. Leaves typically last one year and are then replaced by new ones. These micro-organisms mineralize the discarded leaves and release nutrients that are taken up by the plant. Such relationships are called reciprocal syntrophy because the plant lives off the products of micro-organisms. Many symbiotic relationships are based on syntrophy.

Syntrophic interactions are very important in all living communities, and are important to the Dynamic Energy Budget theory.