434 



Marine Microbiology 



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— S.W. MEDIUM 

 ■— F. W. MEDIUM 



10 

 DAYS 



20 



Fig. 4. Relative viscosities of cultures of Desulfovihrio desiilfuricans. The 



viscosities at 18 C of cultures of Q the salt water strain El Agheila Z, Q the 



fresh water Hildenborough strain and © the Hildenborough strain adapted 



to saline media were measured at intervals after growth had finished. 



30 C and the viscosities of whole cultures relative to distilled 

 water measured in the Ostwald capillaiy viscometer at 18.2 C to 

 18.8 C. All the cultures were fully grown before the first reading 

 was taken. The natural and adapted salt water organisms fomied 

 more mucin than did the fresh water strain. 



Mucous material was formed in very large amounts when 

 the fresh water strain was grown in continuous culture with 

 nitrogenous supplements and a high salt concentration as sul- 

 phate (20). The effluent culture had the consistency of white 

 of egg and separated spontaneously into a layer of zoogleal cell 

 debris and an almost clear supernatant. This material was used 

 for the chemical studies in the mucin reported below. 



The mucin was precipitated from the supernatant fluid 

 either by acidification with trichloracetic acid or by addition 

 of ethanol to 50 per cent. Dialysis and desiccation of the ethanol- 

 precipitated material gave a white powder with a slight anthrone 

 reaction, positive Molisch and ninhydrin reactions; it charred on 



