Cyanothece the process of fixing nitrogen became unfavorable, and natural selection eliminated some of the necessary genes for the nitrogenase protein complex to increase evolutionary fitness. Cyanobacteria turn energy from the sun into chemical energy through oxygenic photosynthesis. Their light-harvesting complex that captures the photons usually includes the pigments chlorophyll a and phycocyanin. A cyanobacterium’s typical blue-green color is a result of the combination of these two pigments. Three "Cyanothece" strains, sp. PCC 7424, 7822 and 8801, have the additional pigment phycoerythrin, which expands the wavelengths of light these species use for energy. Phycoerythrin also gives these three species a brownish-green
Halobacteriales and assisting in the production of energy from light. The process is unrelated to other forms of photosynthesis involving electron transport; however, and halobacteria are incapable of fixing carbon from carbon dioxide. Halobacteria can exist in salty environments because although they are aerobes they have a separate and different way of creating energy through photosynthesis. Parts of the membranes of halobacteria are purplish in color. These parts conduct photosynthetic reactions with retinal pigment rather than chlorophyll. This allows them to create a proton gradient across the membrane of the cell which can be used to create ATP for their own