ABSTRACT
Nitrogen fixation by blue-green algae (cyanobacteria) has long attracted wide attention. According to the composition of photosynthetic pigments, they are roughly grouped into blue-green algae (cyanobacteria), red algae, green algae, brown algae, and so on. This chapter reviews the historical background, recent advances, and future prospects of biotechnology in the algal world. Blue-green algae are also called cyanobacteria because of the prokaryotic nature of their cells. There are good reasons why cyanobacteria have recently attracted great attention from scientific researchers in both basic and applied fields. For example, cyanobacteria are capable of oxygenic photosynthesis and are strikingly similar to higher plant chloroplasts. According to the endosymbiosis hypothesis of evolution, cyanobacteria are regarded as the origin of chloroplasts. The recombinant DNA technology of cyanobacteria started by finding DNA plasmids in various strains. In the latest years, insights have been gained in application of recombinant DNA technology to cyanobacteria, but a great deal of research remains to be done.
