Chapter XII — 165 — Sulfur Bacteria 



by GiETZEN ( 1 93 1 ) . Extensive populations of purple sulfur bacteria along 

 the Holstein coast, growing associated with decomposing plankton includ- 

 ing algae, jellyfish, etc., imparted a distinctly red coloration to the sea. 

 The presence of H2S, microaerophilic or anaerobic conditions, and sun- 

 light appeared to be requisite for maximum development of the purple 

 bacteria. They grow throughout the entire temperature range of the 

 sea. 



The Red Sea and the Vermilion Sea (Gulf of California) were so named 

 because of the frequent red to brownish coloration of the water. Ac- 

 cording to SvERDRUP et al. (1942), certain algae, particularly rnVAoJe^- 

 miiim eryt/iraeum, or dinoflagellates are responsible for the color. Allen 

 (1933) found Prorocentrurn micans, a golden-yellow dinoflagellate, to be 

 responsible for certain occurrences of "red water" off the coast of south- 

 ern California. Extensive patches of "red water" caused by the ciliate 

 protozoan, Mesodinium rubrum, and the shrimp, Munida cokeri, have 

 been reported by Coker (1938). While these or other organisms may 

 sometimes cause "red water," purple bacteria are often overlooked by 

 oceanographers and hydrographers. It is significant that the hydro- 

 graphic conditions in "bloody seas" are generally precisely those which 

 would promote the growth of purple sulfur bacteria; namely, the presence 

 of an abundance of decomposing plankton material which provides for 

 H2S production and reduced oxygen tension. 



Forti (1933) found large numbers of Thio poly coccus ruber, Thiopedia 

 rosea, and Beggiatoa alba in a Sicilian "lake of blood" or "bloody sea." 

 Sulfate reducers in the bottom water provided H2S for the sulfur bacteria. 



Ellis (1932) tells of Rhodothece pendens coloring sea water around 

 Helgoland "as though with rose-red milk of sulfur." Rhabdomonas rosea, 

 Rhodocapsa suspensa, and Amoebobacter roseum are other colored bacteria 

 which live in the sea, according to Ellis. 



Thiopedia rosea was the most abundant organism found in fresh-water 

 plankton by Utermohl (1925). There may be as many as 10,000 of these 

 purple bacteria per ml. of plankton tow. Knipowitsch (1926) found 

 microaerophilic Thiopedia rosea down to a depth of 750 meters in the Cas- 

 pian Sea. 



For further information on the ecology and physiology of the purple 

 sulfur bacteria the reader is referred to the treatises of Bavendamm (1924), 

 Baas Becking (1925), Gietzen (1931), Ellis (1932), and van Niel 

 (1931, 1936). 



In the second category of purple sulfur bacteria are the Rhodobac- 

 terioides or Athiorhodaceae, which do not show intracellular sulfur gran- 

 ules. They grow best in the presence of H2S and are often found associ- 

 ated with Thiorhodaceae and achromic sulfur bacteria. Apparently the 

 Athiorhodaceae are neither as abundant nor as widespread as other types 

 of sulfur bacteria. 



Only one of the seven genera of Rhodobacterioides listed in the Bergey 

 (1939) Manual is described as having a marine habitat, namely, Rhodo- 

 bacterium capsulatum which Molisch isolated from sea water. However, 

 most of the Rhodobacterioides live in water. A more thorough search of 

 the hterature may reveal that most of the genera have marine represen- 

 tatives. 



Baas Becking (1925) recovered a, Rhodococcus or Rhodorrhagus from 

 rotting Fuciis near Moss Beach on the California coast. According to 

 Baas Becking, the sulfur bacteria in brine, brackish water, and fresh- 



