(green sulphur bacteria; order Rhodospirillales)
A family of anaerobic, anoxygenic, photosynthetic bacteria which use sulphide or sulphur as a source of reduction for photosynthesis. Sulphur is sometimes produced from sulphide, but never inside the cells. All species are non-motile. Cells of different species are spherical, curved or straight rods, or ovoid. Cells may be organized into chains, clumps, nets, spirals, etc. Photosynthetic pigments are attached to membrane vesicles linked to, but not continuous with, the cytoplasmic membrane. There are several genera. The organisms are found in sulphide-rich, anaerobic, aquatic environments, often forming greenish or brownish blooms.
Subjects: Plant Sciences and Forestry.