Anoxygenic phototrophic bacteria in eutrophic coastal lagoons of the French Mediterranean and Atlantic coasts (Prevost Lagoon, Arcachon Bay, Certes fishponds)

Sediment samples collected from coastal lagoons on the French Mediterranean (Prevost Lagoon) and Atlantic coasts (Arcachon Bay and Certes fishponds) have been studied in order to determine the population densities and the species diversity of the different groups of anoxygenic phototrophic bacteria (purple sulfur bacteria, purple nonsulfur bacteria and green sulfur bacteria) present in these ecosystems. Several strains of each group were isolated in pure culture and characterized by their physiological properties. The occurrence of purple nonsulfur bacteria in organic rich sediments of the Arcachon Bay and the dominance of purple sulfur bacteria in the Prevost lagoon and Certes fishponds are discussed with respect to their community structure and abundance. The diversity differences of the phototrophic bacterial strains isolated from both environments are also discussed.