ZoBell — 164 — Marine Microbiology 



l-\i Purple sulfur bacteria: — The purple sulfur bacteria, or Rhodothio- 

 hacteria, contain bacteriopurpurin, a photosynthetic pigment. They can 

 utilize radiant energy under suitable conditions, but not all species require 

 sunlight for their activities. Most of them grow best in the presence of 

 H2S. Some of the saprophytic and photosynthetic strains live anaero- 

 bically, but a little free oxygen is required by the autotrophic strains 

 which obtain their energy from the oxidation of H2S. 



The purple sulfur bacteria are classified into two categories upon a 

 basis of the deposition of sulfur. The Thiorhodaceae embracing the 

 genera of the family Chromotioidaceae deposit sulfur intracellularly. 

 They are highly cosmopolitan. Representatives of most genera are 

 aquatic. Some species have been found only in marine habitats. 



From a survey of the literature, Bavendamm (1924) listed the follow- 

 ing Thiorhodaceae which have been observed in salt or brackish water: 

 Thiocystis violacea, Thiocystis rufa, Thiocapsa roseopersicina, Thiosarcina 

 rosea, Lamprocystis roseopersicina, Thiopedia rosea, Amoehohacter gran- 

 ulae, Thiothece gelatinosa, Thiodictyon elegans, Thio poly coccus ruber, Chro- 

 matium warmingii, Thiospirillum jenense, Thiospirillum violaceum, Thio- 

 spirillum rosenbergii, Rhodacapsa suspensa, and Rhodothece pendens. 

 Bavendamm pointed out that these purple sulfur bacteria were found in 

 sunlighted habitats containing H2S. The buffering capacity of sea water 

 permits them to grow. Some of them can tolerate relatively wide temper- 

 ature ranges. Their sulfur metabolism is dependent upon H2S produced 

 by proteolytic saprophytes or sulfate reducers. 



In calcareous mud around the Bahama Islands, Bavendamm (1932) 

 recognized Chromatium okenii, Chromatium weisii, Chromatium minus, 

 Chromatium vinosum, and others. He described them as being actively 

 motile and coming from the sea bottom generously filled with sulfur 

 granules. They often appeared as red clouds in the sea water covering 

 the mud in cultures. Deep down into the mud they formed beautiful, 

 characteristic, wine-red pellicles on the glass walls of culture receptacles. 

 He remarked, regarding bottom biocoenoses, that besides numerous sulfur 

 bacteria of all types, there was a large heterotrophic bacterial population^ 

 including many sulfate reducers. Closely associated with the sulfur bac- 

 teria were many blue-green algae, especially species of Oscillatoria, a few 

 sessile diatoms, and some protozoans. He regarded such an association 

 as being ideal for the activity of the sulfur bacteria. Sulfate reducers pro- 

 vided H2S in the close proximity of algae which, during the hours of day- 

 light, supplied free oxygen. 



In marine bottoms off the northern coast of Russia, Issatchenko 

 (1914) noted the occurrence of Amoehohacter granulae, Thiopolycoccus 

 ruber, Thiosarcina rosea, Thiothece gelatinosa, Chromatium minus, Chr. 

 minutissimum, Chr. rosea, Chr. vinosum, Chr. gobii, and Thiodictyon minus. 

 The last two named sulfur bacteria were described by Issatchenko as 

 new species. 



In the Dreckee mud swamps along the Danish coast, Utermohl (1925) 

 found a maximum of 3000 Chromatium cells per ml. along with 2900 

 Thiopedia cells and several hundred cells of Thiocystis. The combined 

 6000 to 7000 purple bacteria per ml. of water caused a red coloration. It 

 was from similar shallow "red water" sounds that Warming (1875) iso- 

 lated achromic species of sulfur bacteria which were freely mingled with 

 masses of purple bacteria. 



Further data on "red water" or so-called "bloody seas" are reported 



