Anoxygenic photosynthesis is characteristic of:

The photosynthetic bacteria respire without oxygen. No oxygen is evolved in bacterial photosynthesis. Water is not used as a source of reducing power. Instead, hydrogen is obtained either directly or from various types of inorganic and organic compounds, e.g., H2S, aliphatic compounds. Anoxygenic photosynthesis is characteristic of Rhodospirillum. It is a non-oxygenic photosynthetic bacteria.