ABSTRACT
The ability to transfer electrons to a partner organism is an important metabolic feature associated with many physiologically diverse microorganisms. This trait is usually referred to as syntrophism. Syntrophism is a special type of symbiosis between two microorganisms, where the growth of one organism is dependent or highly improved by growth factors, nutrients, or substrates, either removed or provided by the partner organism. Especially among anaerobic microorganisms, cooperation of several metabolic types of bacteria in the food chain is important. Knowledge of the occurrence, diversity, and distribution of these syntrophic consortia is steadily increasing [1,2,3]. Also among Clostridiales, many species can grow in cooperation with syntrophic partners. In this chapter, we review important interspecies electron transfer-based syntrophic conversions and describe the microorganisms involved. Some of the organisms are capable of syntrophic growth on a variety of compounds. In this case, we describe the best-studied conversion. Detailed information on the biochemistry and bioenergetics of syntrophic organisms can be found elsewhere [2,3]. There are probably many other members of the Clostridiales with the ability to grow syntrophically. However, such capacities are only rarely checked for.
