250 iJACTEIllOLOGlCAL CHEMISTRY 



muscle systems. The transfer of phosphate from phos- 

 phopyriivic acid via adenylic acid to glucose, similarly, 

 takes place under appropriate conditions. Enzymes 

 have been obtained from Staph, albus which can bring 

 about all the reactions of the Embden-Meyerhof scheme 

 (see p. 275). Lactic acid is only produced under anaerobic 

 conditions by this organism. There is, therefore, very 

 considerable evidence that the initial stages of bacterial 

 fermentation are very similar to, if not identical with, 

 those of yeast fermentation, and that the variations 

 producing the additional acids and other substances 

 arise in the later stages of fermentation. 



Kluyver, also, regards methylglyoxal as the inter- 

 mediate in these acid fermentations : — 



: /OH 

 CHgCChC^OH > CH3CHO + HCOUH . U, + CO, 



\H 



(methylglyoxal) (methylglyoxal (acetaldehyde) 



hydrate) 



The acetaldehyde gives acetic acid by direct oxidation 

 aerobically, or possibly by dismutation, anaerobically. 

 Kluyver considers that there are three types of fer- 

 mentation brought about by organisms of the Esch. coli 

 group : — 



1. Succinic acid fermentation, which occurs in the 

 absence of cozjrmase, and therefore in the absence of 

 phosphorylation. It takes place by a splitting of the 

 glucose molecule into a four-carbon atom fragment and 

 a two -carbon atom fragment giving tartaric dialdehyde 

 and ethylene glycol respectively, which in turn give 

 rise to succinic acid and to acetaldehyde, as shown in 

 the scheme below. 



Virtanen also suggested that succinic acid arose by 

 splitting of hexosos into f()ur-cai'l)on and two-carbon 

 fragments. 



As a result of studies of the fixation of carbon dioxide 



