Question: What properties of this bacteria allow it to photosynthesise and why is this the only prokaryotes to produce oxygen?

Cyanobacterium answered on 26 Nov 2017:

Cyanobacteria were the first organisms to evolve oxygenic photosynthesis leading to the Great Oxygenation Event about 2.4 billion years ago). Cyanobacteria possess photosystems I and II, which are located on thylakoid membranes in most cyanobacteria. The photosynthesis complex has an enzyme that is able to split water and generate oxygen through a chemical reaction. However, it is not known why other bacteria did not evolve the ability to produce oxygen via photosynthesis.