Bacteriochlorophyll pigments, anaerobic

Anaerobic Sulfide Oxidation. An alternative explanation is that sulfide is oxidized anaerobically in association with phototrophic reduction of C02 to organic carbon (46, 49). This hypothesis is supported by the discovery of considerable quantities of bacteriochlorophyll pigments within and below the suboxic zone (50). The integrated quantities of these pigments appear to exceed that of the chlorophyll a in the overlying oxygenated portion of the eu-photic zone. The light levels at the depth of the bacteriochlorophyll maximum, however, are very low (<<0.1% where Ia is the incident radiation) and the carbon assimilation rates necessary to verify the hypothesis are difficult to calculate or measure. 

The green sulfur bacteria are the "classical" green bacteria. They contain relatively large amounts of chlorobium chlorophyll (bacteriochlorophyll c, d or e), in addition to BChl a. The latter pigment is mainly contained in the cytoplasmic membrane, whereas most of the BChl c is situated in the chlorosomes, oblong bodies of several hundred A diameter that are bound to the cytoplasmic membrane. Green sulfur bacteria are strict anaerobes which are found in fresh water as well as in marine habitats. 

Erythrobacter species synthesize photosynthetic pigments including bacteriochlorophyll a and several carotenoids under highly aerobic conditions, but they can not grow anaerobically even in the light in contrast to typical photosynthetic bacteria [1]. 

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