Researches on Nitrifying Bacteria 425 



the marine strains grow consistently faster in NaCl containing 

 media, but it emphasizes that terrestrial strains also produce 450 

 and 440 A'g of nitrous nitrogen in media 2 and 3 after 40 and 

 50 days of incubation, and 5 /'g in medium 4 with 5% NaCl con- 

 centration. 



This seems to imply that the marine microorganisms are 

 somewhat active in their original environment and that terrestrial 

 bacteria carried in the sea water are able to become active after 

 a lag for adaptation. 



CONCLUSIONS 



The studies on nitrifying bacteria in the marine depth of the 

 Algerian coast have led to the following results: 



(1) All the specimens studied have demonstrated active 

 nitrification. 



(2) The nitrification is more rapid in depths of less than 

 100 m, and slows down proportionally to the depth. For a given 

 sample the upper horizons of a sediment are more active than 

 the lower. 



(3) In the sands covered by marine vegetation, nitrification 

 is more active, even though other bacteria are represented. 



(4) The nitrifying bacteria from a marine origin are more 

 active at salt concentrations equivalent to those prevalent in their 

 natural environment than the terrestrial strains. But the terrestrial 

 bacteria, after a longer lag period, also show a great activity. 



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3. Gran, H. H.: Havets Bakterier og deres Stofskifte. Naturen, Bergen, 27: 



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4. IssATSCHENKO, B. L.: Investigations on the Bacteria of the Glacial Arc- 



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