[Effect of light intensity on the content of bacteriochlorophyll and on the growth of phototrophic marine sulfur bacteria]. / Influence de l'intensité lumineuse sur la teneur en bactériochlorophylle et sur la croissance de sulfobactéries phototrophes marines.

Eight strains of Chromatiaceae isolated from marine sediments are cultivated under light intensities of 50-5000 lx. A decreased in the light intensity brings about an increase in the specific bacteriochlorophyll content and also in the length of development. In certain strains, the increase in pigment contents partly compensates for the loss in light intensity, up to the maximum concentration of bacteriochlorophyll. This mechanism is only a physiological compatibility which ensures the survival of these organisms under feeble light intensities.

[Effect of sunlight penetration on the development of phototrophic sulfur bacteria in marine environment]. / Influence de la énétration de la lumière solaire sur le développement des bactéries phototrophes sulfureuses dans les environnements marins

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.

[Mixed cultures of heterotrophic, sulfate-reducing and sulfur phototrophic bacteria (author's transl)]. / Bactéries fermentatives, sulfato-réductrices et phototrophes sulfureuses en cultures mixtes

In mixed cultures, carbon and electron sources for Desulfovibrio desulfuricans are excreted by Escherichia coli from glucose fermentation. Desulfovibrio produces substrates for Chlorobium strain.

[On the ecology of marine chromatiaceae and chlorobiaceae (author's transl)]. / Sur l'écologie des Chromatiaceae et des Chlorobiaceae marines

Number and genera (types) of phototrophic red and green sulfur bacteria have been determined in the upper layer of eleven marine sediment samples from the euphotic zone in the Mediterranean Sea. Origin and nature of the sediment samples are given as well as their pH, total nitrogen and sulfide content. The results show that the sediments studied did not provide good growth conditions for Chromatiaceae (Chromatium, Thiocystis, Thiocapsa) and Chlorobiaceae (Prosthecochloris). The total number of these bacteria varied in agreement with the total nitrogen content (organic matter) of the samples; the organic matter content is, therefore, of primary importance for the occurrence of the red and green sulfur bacteria in the samples.