Photosynthetic
bacteria are capable of entrapping solar energy and utilizing it for the synthesis
of complex food materials due to the presence of pigments like bacteriochlorophyll
(bacteriopurpurin) and bacterioviridin. Bacterial photosynthesis is also known
as anoxygenic photosynthesis. In bacterial photosynthesis, water is not the
source of electron that acts as reducing agent to convert CO2 into
glucose. The bacteria obtain reducing power from various compounds such as
hydrogen sulphide, thiosulphate or even some organic compounds. No oxygen is
evolved as it does not involve splitting of water. Hydrogen released by various
compounds is picked up by NAD+ which gets reduced to NADH2 acting as
reducing power. NADH2 alongwith ATP, produced generally by entrapping
solar energy are used to reduce CO2 to glucose. The byproduct of bacterial
photosynthesis is sulphur (S).