The Phototrophic Way of Life / Carbon Metabolism of Phototrophic Prokaryotes

The Phototrophic Way of Life / Carbon Metabolism of Phototrophic Prokaryotes: "Cyanobacteria are obligate autotrophs par excellence; however, small molecular weight organic compounds such as acetate, sugars and amino acids are assimilated. In the case of amino acids, the presence of various efficient uptake systems has been interpreted as a means of recovery of leaked organic nitrogen, rather than a true chemotrophic capability (Montesinos et al., 1997). Certain strains of cyanobacteria can grow facultatively as chemoheterotrophs in the dark (Rippka et al., 1979), but even under these conditions all of the photosynthetic machinery is synthesized. This lack of regulation implies that chemotrophy has played no significant evolutionary role in these organisms."