ZoBell — 152 — Marine Microbiology 



teria in samples of sea water. Using similar methods, Gran (1903) ob- 

 tained only negative results with samples of water and mud from Nor- 

 wegian fjords, except very near shore. Similarly, Nathansohn (1906) 

 was unable to demonstrate nitrifiers in the Gulf of Naples beyond the zone 

 which was obviously contaminated by land drainage. Gazert (19066) 

 was rarely able to demonstrate nitrifiers in from 10- to 80-ml. samples of 

 sea water collected off the southern coast of Africa or in the Antarctic on 

 the South Polar Expedition of the research vessel Gauss. Negative re- 

 sults were likewise obtained with sea weeds and diatom tows from the 

 Sargasso Sea as well as off Kerguelen Island in the Indian Ocean. 



ISSATCHENKO (1914) demonstrated the presence of nitrifying bacteria 

 in coastal water of polar Arctic seas and in bottom deposits from off the 

 Murmansk coast. He was unable to find nitrifiers in surface waters of 

 the open ocean. However, he believed that nitrifiers were indigenous to 

 deeper waters and the sea floor. Issatchenko (1926) detected no nitri- 

 fiers where H2S was present in the Black Sea. In shallow water such bac- 

 teria were found in bottom deposits associated with sand and shells, but 

 only infrequently in clay bottoms. Knipowitsch (1926) reported the 

 presence of nitrifying bacteria in surface water of the Black Sea and the 

 Sea of Azov. 



Nitrifying bacteria were demonstrated in all mud samples from Kiel 

 harbor examined by Thomsen (1910). He also found them in mud from 

 the Helgoland channel and the Gulf of Naples. Negative results were ob- 

 tained with samples of sea water collected at considerable distances from 

 land. Likewise Thomsen found no nitrifiers associated with plankton or 

 sessile algae. The nitrifiers which he isolated from marine mud samples 

 were morphologically and physiologically identical with terrestrial Ni- 

 trosomonas. They grew well in sea water and could be acclimatized to 

 higher or lower salt concentrations. They developed readily at 28° C. 



Pirie (191 2) found no nitrifiers while on the Scottish Antarctic Ex- 

 pedition. Liebert (191 5) was unable to isolate nitrifying bacteria from 

 water or bottom deposits of the open ocean. Mud from the North Sea 

 also gave negative results except very near shore. Active nitrifiers were 

 found in the Zuider Zee. Berkeley's (1919) attempts to demonstrate 

 nitrifiers in sea water from off the coast of Vancouver Island were uni- 

 formly negative. 



After finding no evidence of nitrification in 25- to 150-ml. samples of 

 sea water collected from around American Samoa and Tortugas, Florida, 

 LiPMAN (1922) concluded that nitrifying bacteria were not present in the 

 open sea. However, he obtained good nitrification in samples of bottom 

 deposits from nearly all stations. Similar results were reported by 

 Harvey (1928). 



From their rather extensive investigations, Waksman et al. (19336) 

 concluded that, beyond the zone of land drainage, surface sea water has 

 either no nitrifying bacteria or only very few. On the other hand, active 

 populations of nitrifying organisms were found in bottom deposits. 



Similar conclusions were reached by Carey (1938) who has reviewed 

 the literature on the occurrence of nitrifying bacteria in the sea. She 

 found active nitrifiers in most samples of bottom deposits and in surface 

 water samples collected near land. Water samples collected far from 

 land, at depths ranging from 10 to 200 meters, gave negative results. Sam- 

 ples of mud from great depths produced nitrite very slowly and in exceed- 

 ingly small amounts. Concentrated diatom tows, copepod tows, and 



