Researches on Nitrifying Bacteria 423 



marine species develop equally well in media of weak and 

 strong salinity. (Ubiquitous species). With terrestrial species, on 

 the contrary Yankovitch and Yankovitch (6) have demonstrated 

 that the beginning of nitrification is slower when the salt concen- 

 tration is raised. Therefore, we have compared two marine strains, 

 one isolated from ooze at a depth of 63 m (strain V) and the 

 other from Castiglione Matte (Strain M), with two terrestrial 

 strains taken from innocuous soils. 



These sti-ains, purified physiologically by successive transfer 

 in the selective Omeliansky medium, were seeded in the same 

 medium with various degrees of salinity. 



The curves (Fig. 4) provide a comparison of the lag phase 

 and lag phases of the marine nitrite-producing organisms with, 

 those of terrestrial strains, in media of increasing salinity. It is 

 seen that lag phase of the terrestrial strains is much more affected 

 by the increase of NaCl concentration than the strains of marine 

 origin, but they do eventually grow in a concentration of 5% 



30 40 50 60 70 

 DAYS 



Fig. 4. Effect of NaCl concentration on the growth of Marine (A) and Ter- 

 restrial ( B ) nitrifying bacteria. 



