Oxygenic photosynthesis occurs in
(2) Oscillatoria is a photosynthetic cyanobacterium. In this, during photosynthesis water is electron donor and oxygen is a by-product, i.e., oxygenic phorosynthesis occurs. Rhodospirillum and Chlorobium are non-oxygenic photosynthetic, purple non-sulphur and green-sulphur bacteria.
Chromatium is purple sulphur bacterium, also a non-oxygenic photosynthetic.