THE FORMATION OF SPORES BY BACTERIA 



119 



8 



4 8 12 



TIME , HOURS 



Figure 6. Effect of a-picolinic acid on the sporulation of Bacillus cereus T. 



quite surprising ( see Figure 6 ) . An examination of this figure will show 

 that a-picolinic acid, when added to the culture while the pH is still 

 dropping, interferes with the subsequent utilization of the acids, while 

 the pH remains low and no spores result. If this material is added to 

 the culture after the pH begins to rise, there is no eflPect; the pH rises 

 normally, and the result is a normal spore crop. This inhibitor may, 

 therefore, interfere with the development of the adaptive enzyme re- 

 quired for the utilization of the acetic acid. 



In view of the unexpected result with a-picolinic acid, we felt that 

 we should try other pyridine carboxylic acids. Table I gives the results: 

 a-picolinic acid was the only acid able to inhibit sporulation. 



TABLE I 



Effect of Pyridine-Carboxylic Acids on the 

 Sporulation of Bacillus cereus T. 



Compound Added 



Sporulation 



None 



Nicotinic Acid (Pyridine 3-Carboxylic Acid) 



Isonicotinic Acid 



Quinolinic Acid 



Pyridine 2:4 Dicarboxylic Acid 



Pyridine 2:5 Dicarboxylic Acid 



Dipicolinic Acid (Pyridine 2:6 Dicarboxylic Acid) 



a-Picolinic Acid (Pyridine 2-Carboxylic Acid) 



+ 

 + 

 + 

 + 

 + 

 + 

 + 



