ECOLOGY AND PHYSIOLOGY OF PHOTOTROPHIC BACTERIA AND SULFATE-REDUCING BACTERIA IN MARINE SALTERNS

Marine salterns are habitats for a large variety of halophilic bacteria. In the anoxic zones, halophilic sulfur bacteria develop mainly at the sediment surface, but only a few of them have so far been isolated from such environments. Among the phototrophic sulfur bacteria that sometimes form purple layers underneath the green cyanobacterial layers, members of the genera Ectothiorhodospira, Chromatium (C. salexigens), Thiocapsa (T. halophila) were isolated. They grow by using sulfide as an electron donor. In the marine salterns, sulfide originates from active sulfate reduction. Among the halophilic sulfate-reducing bacteria, only Desulfovibrio halophilus and Desulfohalobium retbaense have so far been isolated. The ecology and physiology of both kinds of bacteria are discussed in this paper.