Chemically-Mediated Interactions in Microalgae

Abstract

Chemically mediated interactions between microalgae and between microalgae and other organisms, are widespread in nature. They are important in structuring algal communities, bloom formation, algal development, and they affect the productivity of algae. In recent years understanding of these types of interactions has greatly improved, but in many cases the exact mechanisms are still little understood, and the actual bioactive compounds are not known. Many instances of allelopathic interactions have been recorded, including the presence of autoinhibitors in some algae. Some of the allelopathic compounds identified include free fatty acids (e.g. in green algae), polyunsaturated aldehydes (in diatoms) and the alkaloid cylindrospermopsin (in cyanobacteria). Other chemically-mediated interactions include pheromones and hormones which affect algal reproduction and development. Finally, there is some evidence for microalgae affecting bacterial quorum sensing, and for quorum sensing in cyanobacteria.