ENZYMES DORMANT IN THE INTACT SPORE 115 



longed period of endogenous metabolism, a slow germination paralleled the 

 oxidation of glucose. The lowering of the glucose concentration requirement 

 for germination was probably due to a metabolic contribution to germina- 

 tion from the endogenous reserves. However, at higher concentrations glu- 

 cose acted both as a substrate for oxidation and as a germinating agent. 



The glucose oxidation results indicated that this system was clearly dor- 

 mant in the intact spore and required heat-activation for its expression. More 

 direct evidence for the existence of the glucose-oxidizing system in the intact 

 spores was the demonstration of glucose oxidation in DPN supplemented 

 extracts of spores. This raised the question: did rupturing the spore com- 

 pletely remove the dormancy of the glucose-oxidizing system? Thus a com- 

 parison was made of glucose oxidation by spore extracts prepared from un- 

 heated dormant and heat-activated spores either by sonic disintegration or 

 by grinding. It was clear that only part of the activity was observed in ex- 

 tracts of dormant spores. Heat activation prior to rupture increased the 

 activity in subsequent extracts by 250%. This difference could not be at- 

 tributed to a difference in rupture of the spores. Thus the activity observed in 

 extracts of unheated spores must be in a dormant state in intact spores; other- 

 wise its activity would be detected by the procedures we used. Physical dis- 

 ruption thus liberated a part of the respiratory system. 



We have seen previously that the age of the spore prior to activation also 

 influenced the glucose-oxidizing capacity. The increase in this capacity dur- 

 ing aging could be caused by either a change in the mechanism controlling 

 dormany, or by a quantitative increase in the activity of some component 

 of the system itself. An examination was made of the activity of extracts 

 of heat-activated spores of various ages. Extracts of freshly harvested spores 

 supplemented with DPN were as active as those of aged spores. Thus the 

 reason that heat-activated freshly prepared spores did not oxidize glucose 

 was probably not a modification in the dormancy-regulating mechanism. On 

 the other hand, it seemed probable that aging led to a quantitative increase 

 in activity in the system either through loss of an inhibitor and/or produc- 

 tion of some cof actor such as DPN. The observations of Swartz et al (1956) 

 on heat-activated enzyme systems in bacteria may represent an example of 

 the former. 



A comparison of glucose oxidation of germinated spores and non-germi- 

 nated but heat-activated spore preparations was made. The experiment was 

 undertaken to establish whether heat-activation in the absence of germina- 

 tion (brought about any quantitative alteration in the enzyme system. The 

 results indicated that germination only slightly increased the rate of glu- 

 cose oxidation over that of the heat-activated spores. At the same time it 



