76 Perspectives in Microbiology 



Glycolytic Pathway. After drawing your attention to 

 these new types of sugar decomposition, I must not neglect 

 to say that a few species of bacteria apparently still persist 

 in using the old-fashioned glycolytic mechanism. I say 

 "apparently" because with several of these bacteria the sup- 

 porting evidence is not conclusive. The most extensive evi- 

 dence for a glycolytic mechanism has been obtained with 

 E. coli (3) and with Streptococcus faecalis (19). In particu- 

 lar, the formation and decomposition of fructose- 1-6-diphos- 

 phate, the characteristic compound of the glycolytic path- 

 way, has been demonstrated with these organisms. The oc- 

 currence of glycolysis in Clostridium perfringens is strongly 

 indicated by the presence of aldolase, the enzyme convert- 

 ing fructose diphosphate to triose phosphate, which was 

 demonstrated by Bard and Gunsalus (1). With Clostridium 

 thermoaceticum and Lactobacillus casei, the distribution 

 patterns of C^^ in products obtained in the fermentation of 

 C^Mabeled glucose are indicative of a predominantly gly- 

 colytic pathway, but detailed enzymatic studies are lacking. 



The available information on glucose decomposition by 

 bacteria may be summarized by saying that at least four 

 distinctly different mechanisms are known, and some of 

 these have recognizable variations. These mechanisms are 

 not mutually exclusive, since at least two of the systems have 

 been found in P. fluorescens and E. coli. Probably com- 

 binations of these systems will be found in many if not all 

 bacteria. It is impossible at present to say whether these 

 are the only pathways of sugar breakdown that exist in 

 bacteria or to estimate which pathways are used more com- 

 monly. Clearly this is an area of research where much has 

 been accomplished but where much still remains to be 

 done. 



OXroATION OF PYRUVATE AND ACETATE ^ 



A further step in the decomposition of carbohydrate is 

 the oxidation of pyruvate to acetate. This process has been 



