Evolution and Diversity

Cyanobacteria are photosynthetic gram negative bacteria formerly known as blue-green algae as they were long thought to belong to the plant kingdom. A feature shared by cyanobacteria and plants is their ability to perform oxygenic photosynthesis. According to the endosymbiont theory cyanobacteria are in fact the origin of chloroplasts, the organelles which harbor the plant`s photosynthetic machinery. As evidenced by fossils, cyanobacteria have been among the earliest life forms on earth and have been involved in the formation of the earth’s atmosphere. Up to now the production of oxygen by cyanobacterial photosynthesis contributes to keeping the balance of O2 and CO2 on our planet.

During the course of evolution, cyanobacteria have adapted to almost every ecological niche, including the most extreme ones. They can be found in freshwater lakes and oceans, as well as in deserts, hot springs, and even in the arctic ice. The adaptability of cyanobacteria is based on their enormous diversity in species and strains and their ability to synthesize structurally and functionally diverse natural products. Due to this enormous biodiversity among cyanobacteria only a small proportion of cyanobacterial species and their natural products have been characterized to date. Besides, phylogenetic analyses evidence the early evolution of biosyntheses of natural products in cyanobateria. During evolution cyanobacteria have passed on their biosynthetic genes by horizontal gene transfer to other bacterial species indicating the huge potential of this group of microorganism.

Only in the last years cyanobacteria have been recognized as a potent source for numerous biologically active natural products. To date about 1,000 molecules of cyanobacterial origin are known, among which are many pharmacologically interesting compounds showing e.g. anticancer, antimicrobial and hypertension lowering activities. It is now recognized that these organisms have a huge potential for the isolation of a plethora of pharmacologically relevant compounds. This potential is further enhanced by the possibility to optimize identified structures by means of combinatorial biosynthesis. However, the relative disregard of cyanobacteria in the past compared to other microbial sources of natural products, as well as the huge diversity and biological activities of their products, make them an attractive source for the pharmaceutical industry as well as many other industrial products and applications today.