[Effect of sunlight penetration on the development of phototrophic sulfur bacteria in marine environment].

Bottles of medium were inoculated with both strains of Chromatiacea and Chlorobiaceae (mixed cultures) and immersed at differnt depths in the marine coastal waters of the Marseilles basin (France). After development, the in vivo absorption characteristics of the cells show the effect of the daylight penetration on the selective growth of photorophic sulfur bacteria. With depth, sunlight selects Chlorobiaceae rich in brown carotenoid pigments to the detriment of Chromatiaceae.