80 H. HALVORSON et al. 



PYRUVATE HYPOTHESIS 



The hypothesis that the germination agents are metabolized 

 to a common intermediate which is responsible for germination, 

 is supported by the above findings that pyruvate may be derived 

 from alanine, adenosine or glucose. If germination requires the 

 formation of products of pyruvate oxidation, one would expect 

 that precursors of pyruvate would support a germination which 

 was sensitive to inhibitors of pyruvate oxidation, whereas 

 products of pyruvate oxidation would permit germination which 

 was insensitive to these inhibitors. An example of this was 

 observed for spores of B. cereus-^. Germination which normally 

 occurs in the presence of glucose, pyruvate, 6PG, R5P or 2KG 

 was inhibited by hexetidine, an inhibitor of pyruvate oxidation. 

 The inhibition was reversed by cocarboxylase. In the presence 

 of hexetidine, pyruvate and NH3 accumulate. Germination in 

 the presence of acetate, however, was insensitive to hexetidine. 

 Similar results have been obtained with arsenite^^. Recently 

 Church^-^ has found that intermediates of the tricarboxylic acid 

 cycle, fumarate, succinate, citric, and r/^-aconitic acid will 

 initiate germination. One might postulate, for example, that 

 germination requires energy, the formation of a-keto acids for 

 amino acid synthesis or of organic acids which act as seques- 

 tering agents with the heavy metals present in spores. Although 

 a further clarification of this will require further experimenta- 

 tion, it is clear that germination involves the initial mediation of 

 energy-yielding reactions in a system characterized by a burst of 

 degradative reactions. 



THE ELECTRON TRANSPORT SYSTEM AND ITS REGULATION BY DPA 



The pyruvate hypothesis, which we have just outlined, places 

 also an increasing dependence of germination on the activation 

 and functioning of the electron transport system of the spores. 

 Since this system is essentially absent in the dormant spore, its 

 activation is essential to oxidative reactions. Although one might 

 a priori invoke a number of hypotheses to explain the inactive 



