Chapter XII — 163 — Sulfur Bacteria 



bacteria because they contain sulfur granules and no photosynthetic pig- 

 ments. Mass cultures often appear white owing to the formation of sul- 

 fur. According to Ellis (1932), the Leucothiobacteria includes all of the 

 colorless sulfur bacteria. He does not regard the T hiohacillus group as 

 "sulfur bacteria" because, unlike the Achromatiaceae and Beggiatoaceae, 

 they do not store sulfur in their cells. Some workers, on the other hand, 

 employ the term "sulfur bacteria" to embrace all classes of bacteria 

 which either oxidize or reduce sulfur or its inorganic compounds, including 

 sulfate reducers and all colorless forms which oxidize sulfur or its com- 

 pounds, as well as the purple sulfur bacteria, regardless of whether the 

 cells have sulfur granules or not. 



There are several marine representatives of the Achromatiaceae and 

 Beggiatoaceae. In fact, most known species grow equally well in salt 

 water and fresh water. They, along with purple sulfur bacteria, are abun- 

 dant in shallow water where H2S is being produced, particularly in pools 

 among rocks where seaweed is undergoing decomposition, 



Achromatium oxaliferum occurs in sea water as well as in fresh water, 

 according to Bavendamm (1924) and Ellis (1932). It oxidizes H2S to 

 sulfur which may be desposited intracellularly along with calcium oxalate 

 granules : 



2 HoS + O2 = 2 H2O + 2 S 



Bavendamm also found Achromatium gigas in brackish water. Achro- 

 matium millleri was isolated from sea water off the Danish coast by 

 Warming (1876). 



HiNZE (1903) discovered Thiophysa volutans in fine sand in the Gulf of 

 Naples. It oxidizes H2S to free sulfur or sulfate. At low oxygen tensions, 

 ceUs contain sulfur granules but in the presence of an excess of oxygen, the 

 sulfide is oxidized to sulfate. Ellis (1932) claims that Thiophysa volutans 

 is confined to marine waters. 



MoLiscH (191 2) found Thiospira hipunctata growing in the sea. It 

 oxidizes H2S and deposits sulfur granules intracellularly. Molisch also 

 found Beggiatoa marina associated with rotting marine algae. The latter, 

 like other species of Beggiatoa, is a filamentous form showing undulatory 

 creeping. It oxidizes H2S to sulfur which is deposited as intracellular 

 granules. 



Beggiatoa mirahilis was isolated from sea water by Cohn (1865). 

 Warming (1875) found Beggiatoa mitiima in the sea. The last two named 

 species, together with Beggiatoa arachnoides, Beggiatoa alba, and Beggiatoa 

 leptomitijormis, were identified in calcareous mud off the Bahama 

 Islands by Bavendamm (1932). The occurrence of Beggiatoa species in 

 the sea has been reported by many workers (Bavendamm, 1924). 



Thiothrix annulata and Thiothrix mari^ia, whose cells contain sulfur 

 granules, were isolated from rotting algae in sea water by Molisch (191 2). 

 He likewise found Thiothrix nivea and Thiothrix tenuis in Trieste harbor 

 sea water and in the Baltic Sea. Ba\^ndamm (1924) and Ellis (1932) 

 have reported the presence of Thiothrix species in the sea. 



According to Bergey et al. (1939), the ocean floor is the habitat of 

 Thioploca schmedlei, a colorless Beggiatoa-\\ke. organism which deposits 

 sulfur granules in the cell. Bavendamm (1932) expressed surprise at not 

 finding species of Thioploca in calcareous mud around the Bahama Is- 

 lands. Ellis (1932) records that Thioploca schmedlei and Thioploca 

 ingrica live in the sea. 



