QUALITATIVE CATABOLIC REACTIONS OF BACTERIA 77 



4. C 6 H 12 O 6 = CH 3 .CH 2 .CH 2 .COOH + 2C0 2 + 2H 2 . Pure butyric 

 acid fermentation. 



5. C 6 Hi 2 6 = 2CH 3 CH)H + 2C0 2 . Pure alcoholic fermentation. 



6. 2C 6 H 12 O G + H 2 = 2CH 3 .CH#)H.COOH + CH 3 .COOH + 

 C 2 H 5 OH' + 2CO 2 + 2 + 2H 2 . The type of fermentation produced 

 by B. coli in dextrose broth. 1 



The sugars containing six carbon atoms appear to be somewhat 

 more utilizable than their corresponding alcohols: thus, the Shiga 

 bacillus (B. dysenteriae) can not ferment mannite; it can, however,, 

 readily ferment dextrose. This would suggest that the aldehyde 

 group CHO is somewhat more readily attacked than the alcohol 

 group CH 2 OH , for mannite has no aldehyde group and dextrose 

 has an aldehyde group. The alcohols in general appear to be less 

 readily acted upon by bacteria than are the corresponding aldehydes or 

 even organic acids, provided the latter are not too greatly dissociable. 



The products of fermentation of higher alcohols, as mannite, by 

 bacteria are somewhat different from those of the corresponding sugars 

 (aldoses). The chief points of difference, according to our present 

 knowledge, consist principally in the production of more alcohol 

 when the 'higher alcohols are utilized than when the corresponding 

 aldoses are concerned. This has been worked out satisfactorily for 

 certain bacteria, notably the colon and the typhoid bacilli, by Harden. 2 

 It is not definitely known for many other organisms. The gas-forming 

 bacteria, as a rule, produce more gas and more alcohol from the alcohols 

 of the Ce series than from their corresponding aldoses. This gas 

 formation appears to result from the decomposition of formic acid 

 by the activity of a specific enzyme, formiase, according to the equa- 

 tion HCOOH = CO 2 + H 2 O. 3 Thus, B. coli and related gas-forming 

 bacteria, according to this theory, produce the ferment, formiase, 

 while B. typhosus, which also produces formic acid from the decom- 

 position of dextrose, does not possess this ferment and consequently, 

 forms no gas in sugar solutions. Formic acid is, therefore, somewhat 

 prominently represented among the decomposition products of carbo- 

 hydrates by the typhoid bacillus, while formic acid is either not 

 present or present in small amounts in corresponding cultures of colon 

 bacilli. 4 



The qualitative changes produced in fats and lipoidal substances 

 by bacteria are not well known. 



1 Kruse, Allgemeine Mikrobiologie, p. 294. 



2 Jour. Hygiene, 1905. 



3 Franzen and Stuppuhn, Ztschr. f. physiol. Chem., 1912, Ixxvii, 129. 

 Clark, Science, November 7, 1913. 



