Green Sulfur Bacteria

(chlorobacteria), microorganisms of the group of sulfur bacteria that contain chlorophyll and assimilate carbon dioxide by means of solar energy. The bacteria massed together have a saturated green coloration. They carry on photosynthesis in anaerobic conditions without giving off oxygen; hydrogen sulfide is the hydrogen source, but sulfur is not stored in their cells. Green sulfur bacteria contain bacteriochlorophylls, which have maximum absorption of radiation with wavelengths of 450–800 nanometers (this distinguishes green sulfur bacteria from green algae and from purple sulfur bacteria), as well as photosynthetically active carotenoids. All green sulfur bacteria be-long to the family Chlorobacteriaceae. They are represented by the mobile, nonspore-carrying bacillus with a long, polar flagellum—Chlorobium limicola, which forms chains—and Pelodictyon clathratiforme, whose cells typically form a loose net. Green sulfur bacteria live in bodies of fresh and salt water, in which they facilitate the accumulation of organic substances and take part in the sulfur cycle.