The defining feature of, such as cows and goats, is a stomach called a.The rumen contains billions of microbes, many of which are syntrophic. One excellent example of this syntrophy is. Some anaerobic fermenting microbes in the rumen (and other gastrointestinal tracts) are capable of degrading organic matter to, and hydrogen.The accumulatinginhibits the microbe’s ability to continue degrading organic matter, but the presence of syntrophic hydrogen-consuming microbes allow continued growth by metabolizing the waste products.In addition, fermentative bacteria gain maximum energy yield whenare used as electron acceptor with concurrent2production.Hydrogen-consuming organisms include, sulfate-reducers,, and others.Some fermentation products, such aslonger than two carbon atoms, alcohols longer than one carbon atom, and branched-chain and aromatic fatty acids, cannot directly be used in.
In acetogenesis processes, these products are oxidized toand H2by obligated proton reducing bacteria in syntrophic relationship with methanogenicas low H2partial pressure is essential for acetogenic reactions to be thermodynamically favorable (G < 0).
The number of bacterial cells that live on or in the human body, for example throughout the alimentary canal and on the skin, is on the same order of magnitude as human cells.These microbes are, for instance for the digestive and the immune system to function.
Another example is the many organisms that feed onor dung. Adiet consists mainly of, theof which is transformed intobyin the cow’s. These micro-organisms cannot use the lipids because of lack ofin the intestine, so the cow does not take up all lipids produced. When the processed grass leaves the intestine as dung and comes into open air, many organisms, such as the, feed on it.
Yet another example is the community of micro-organisms in soil that live offlitter. Leaves typically last a 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. Manyrelationships are based on syntrophy.