Diversity, Ecology, and Taxonomy of the Cyanobacteria

Abstract

The cyanobacteria are photosynthetic prokaryotes possessing the ability to synthesize chlorophyll a and at least one phycobilin pigment; typically water acts as the electron donor during photosynthesis, leading to the release of oxygen. They are by far the largest group of photosynthetic prokaryotes, as judged by their widespread occurrence, frequent abundance, and morphological diversity. Not only are they represented at the present day in most types of illuminated environment, except for those at lower pH values, but they have one of the longest geological records (Schopf and Walter, 1982). Much of the earth's original atmospheric oxygen was probably formed by organisms quite similar to modern cyanobacteria (Knoll, 1985) and they are still responsible for a considerable proportion of photosynthetic oxygen evolution in the oceans.