120 



MOLECXn.ES, VIRUSES, AND BACTERIA 



In Figure 7 we show the eflFect of succinic acid on the inhibition of 

 sporulation by a-picohnic acid. Succinic acid reverses the inhibition, 

 even when it is added as late as five hours after growth starts. In view 

 of this, we have tested a large number of other acids, including some 

 amino acids, for their ability to reverse this inhibition. The results are 

 shown in Table II. It is to be noted that all of the intermediates in the 

 TCA and the glyoxalic-acid shunt reverse this inhibition except fumaric 

 acid, ketoglutaric, and glyoxalic acid. In addition, the inhibition is re- 

 versed with a number of other acids. Most of these can readily enter 

 the cycles mentioned. Succinic acid proved to be the best reversing 

 agent, in that it would reverse the inhibition in concentrations smaller 

 than any of the other substances tested. Among the amino acids, as- 

 partic acid and asparagine were the only ones that proved effective. 



From the above results we were led to suspect that the glyoxalic 

 acid shunt was the one needed for the synthesis of spore protein and 

 dipicolinic acid. By these findings we were encouraged to investigate 

 other inhibitors to see if we could cast further light upon this problem 

 and get further indications as to whether or not the tricarboxylic-acid 

 cycle or the glyoxalic shunt was involved. 



Before pursuing this problem, we investigated the effect of metals 

 on the inhibition with a-picolinic acid, because this compound is a 

 strong chelating agent and its effect may be due to the removal of some 

 essential metal ion. In order to interpret these experiments one needs 



8 



PH 6 



Normal 

 Culture 



2.0 X 10 8 

 1.4 X 10 8 



/ No succinate added 

 / {M/1200) 



/CI picolinic added 

 (1.2 X 10-3 M) 



o--^---D -D <I03 



Latest succinate can be reversing agent 

 \ I I 







4 8 



TIME, HOURS 



12 



Figure 7. Reversal by succinate of the inhibition of sporulation of Bacillus 

 cereus T. by a-picolinic acid. 



