158 HARLYN HALVORSON 



glucose — \ — ► glucose-6-P04 



I DPN |tpn 



gluconate — V^ 6-PO^-gluconate 



i. . . oe 



2-keto gluconate 



Mg^tATP 



2-keto-6-PClf gluconate 



1 

 ? 



pentose 



I 



ATP 



gPJ Via TCA or 



alanine-*pyruvate-Mi^ "active acetate" °^^ ^y^" > CC^*H20 



11 ATP.MotNHjOH 



1' 



X aceio hydroxomate 



Fig. 15. Pathways of carbohydrate metabolism in spores of B. cereus 

 var. terminalis. 



is inhibited by the presence of glucose (Stanier, 1951). The mechanism 

 of such inhibitions, called "glucose effects," is little understood. Bacterial 

 spores, on the other hand, germinate in the presence of glucose and, there- 

 fore, presumably escape such "glucose effects." One possible explanation is 

 that in systems demonstrating "glucose effects" glycolytic or HMP path- 

 ways are usually operative. If the inhibition is actually from some product 

 of either of these two pathways, it would be lacking in the glucose metabo- 

 lism of the spores. Such an escape of "glucose effects" is of selective value 

 to the spore, which must obviously increase at least part of its enzymic pat- 

 terns during germination. 



The enzyme reactions presented here also suggest a biochemical relation- 

 ship between the germinating agents for B. cereus var. terminalis. In the 

 presence of adenosine, additions of alanine, high levels of glucose, or pyru- 

 vate stimulate germination (Church, 1955). The glucose dehydrogenase 

 has a high Ks value, thus requiring high levels of glucose to saturate the 

 system. Both glucose and alanine serve as precursors of pyruvate. An in 

 vivo inhibitor of pyruvate oxidation by spores inhibits their normal germi- 

 nation in the presence of L-alanine and adenosine. The inhibition of both 



