GENERAL MICROBIOLOGY - T.P. Pyrog - 2004

18. PHOTOTROPHIC BACTERIA AND PHOTOSYNTHESIS

The ability to use light as an energy source required for growth is characteristic of two fundamentally different groups of Bacteria.

The first group includes Purple and green bacteria. According to the 9th edition of Bergey's Manual of Systematic Bacteriology, these bacteria belong to the Class Anoxyphotobacteria. They cannot use Water as a hydrogen donor (unlike green plants) and instead require Donors with a higher reduction potential (hydrogen sulfide, hydrogen, or Organic compounds). Consequently, their Photosynthesis occurs without oxygen evolution (anoxygenic photosynthesis). Bacteria of this group are typically aquatic organisms inhabiting both fresh and marine waters. Their red, orange, or green coloration is due to the presence of chlorophylls and carotenoids.

The second group comprises cyanobacteria. They use water as a hydrogen donor and evolve oxygen, meaning they perform oxygenic photosynthesis. The photosynthetic process in cyanobacteria is identical to that of green plants. The pigment system of cyanobacteria includes chlorophyll a, carotenoids, and phycobiliproteins.



Last update: 12/08/2026

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