Distribution and Ecology of Azotohacter in the Black Sea 



389 



similar to that of Azotohacter. The other microorganisms showed 

 considerably lower nitrogen fixing ability (Table 3). 



TABLE 3 



Nitrogen-Fixing Ability of Microorganisms Isolated From Water 

 AND Sediments of Different Regions of the Black Sea* 



* The regions of the investigation are shown in Tables 1 and 2. 



Thus the results of the field and laboratory observations 

 give the reasons to believe that Azotohacter and Clostridium 

 have an essential importance in the process of nitrogen fixation 

 in the muds of the Black Sea, and Azotohacter has the same im- 

 portance on the surface of macrophytes too. However, in water 

 of the open sea, especially in the deep-water regions, the leading 

 role in nitrogen fixation belongs, apparently, to some other 

 organisms. The participation of Clostridium in this process in 

 water of the deep-water regions of the open sea probably falls 

 off completely. 



