436 Marine Microbiology 



cell wall material. Therefore cell walls of the Hildenborough 

 strain, harvested from continuous culture when no detectable 

 mucin was being formed, were prepared by disruption with glass 

 ballotini and repeated washing ( 22 ) . The product was hydrolysed 

 and analysed qualitatively for amino-acids and sugars. Those 

 observed are recorded in Table 3; the cell wall preparation dif- 

 fered from the mucin in containing diaminopimelic acid. Hy- 

 drox^'proline was scarcely detectable and the relative concen- 

 tration of other amino acids was different from those in mucin 

 hydrolysates. Mannose was not present, carbohydrate being 

 represented by glucosamine and a material having the Rf of 

 ribose. 



TABLE 3 



Amino-acid Material Contained in Stationary Populations of Salt and 

 Fresh Water Strains of D. Desulfuricans 



If follows from these observations that the mucin produced 

 by these bacteria is not over-produced cell wall or capsular ma- 

 terial. It is a mucopolymannoside produced in response to media 

 of appropriate salinity. 



(Ill) "Free Amino-Acid Material" 



Mattick et al. (13) have used chromatography of the ninhy- 

 drin-positive material released from bacteria by acidification for 

 taxonomic studies. During an investigation of the applicability 

 of this procedure to the sulphate-reducing bacteria we observed 



