CH. V] VARIATIONS IN FERMENTING POWER 61 



I. Different strains may possess different fermenting 

 properties. 



The typical pneumococcus ferments saccharose (a di- 

 saccharide), mannite (a polyatomic alcohol) and inulin (a 

 starch). Its power to ferment inulin is a feature upon 

 which reliance is placed in differentiating the organism from 

 other members of the streptococcus group. Eyre, Leatham 

 and Washbourn (1906) found that out of 14 different 

 strains examined by tliem 4 failed to ferment inulin, an equal 

 number failed to ferment mannite and 3 failed to ferment 

 saccharose. 



Strains of the meningococcus obtained from epidemic 

 and from sporadic cases of meningococcal meningitis exhibit 

 differences in their fermenting properties (Batten). Arkwright 

 (1909) describes several strains of the meningococcus which 

 failed to ferment any sugars — in some cases " permanently," 

 and in other cases for varying periods after their isolation. 



Wilson (1908) analyses the "sugar reactions" in the case 

 of* 44 gas producing coliform organisms obtained from the 

 urine of patients suffering from cystitis and pyelitis. The 

 various strains showed an extraordinary diversity in their 

 fermenting properties. 



Many observers have recorded marked differences in fer- 

 menting properties between different strains of dysentery 

 bacilli. One example will suffice. Bahr (1912) collected 28 

 different strains of dysentery bacilli in Fiji. He tested the 

 power of these strains to ferment six sugars (dextrose, 

 dulcite, maltose, saccharose, lactose and mannite) with the 

 result that the 28 strains formed no less than 7 distinct 

 groups. The addition of further sugars for test purposes 

 would no doubt have revealed still more varieties. 



Arkwright (1909) mentions a strain of gonococcus, isolated 

 from the urethral discharge in a case of acute gonorrhoea, 

 which fermented glucose and maltose but not saccharose, 

 thus resembling most strains of the meningococcus and 

 differing from the typical gonococcus which is a non-fermenter 

 of maltose. W. B. M. Martin (1911) describes an atypical 

 strain of the gonococcus, isolated in pure culture from the 



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