Photosynthesis in bacteria

Photosynthesis in bacteria

Though we study about bacterial photosynthesis as the last part, bacterial photosynthesis formed first and foremost in evolution. Bacteria does not have specialized structures like chloroplast. It has a simple type of photosynthetic apparatus called chlorosomes and chromatophores (Table 13.6). Van Neil (1930) discovered a bacterium that releases sulphur instead of oxygen during photosynthesis. Here, electron donor is hydrogen sulphide (H₂S) and only one photosystem is involved (PS I) and the reaction centre is P₈₇₀. Pigments present in bacteria are bacteriochlorophyll a, b, c, d, e and g and carotenoids. Photosynthetic bacteria are classified into three groups:

1.           Green sulphur bacteria. Example: Chlorobacterium and Chlorobium.

2.           Purple sulphur bacteria. Example: Thiospirillum and Chromatium.

3.           Purple non-sulphur bacteria. Example: Rhodopseudomonas and Rhodospirillum.