130 MOLECULES, VIRUSES, AND BACTERL^ 



is concerned. They are refractile, like normal spores; they undergo 

 germination with ordinary germination nutrients, as ordinary spores 

 will; and they are resistant to octyl alcohol. They are extremely sensi- 

 tive to heat, most of them being killed at 65° C. in less than 15 minutes. 

 Their heat resistance is no greater than that of vegetative cells. 



Both of these inhibitors can be reversed by dipicolinic acid added 

 from the outside as much as seven to nine hours later. In the presence 

 of DPA, the spores produced are heat-resistant. A similar experiment 

 cannot be made with diethyl pimelate, because this substance cannot 

 be added to the cultures at the beginning. But if this is added to the 

 culture at seven hours, we find that most of the spores are heat-sensi- 

 tive, whereas if we add dipicolinic acid at the same time, all of the 

 spores are heat-resistant. 



To summarize our data, they seem to indicate that the glyoxylic- 

 acid shunt may be involved in the synthesis of spore material and dipi- 

 colinic acid. Apparently some of the enzymes needed in this shunt are 

 not present in vegetative cells but are produced as adaptive enzymes 

 after the sugar has been used up. Succinic acid appears to be important 

 as an intermediate in the synthesis of the spore material, and perhaps 

 also in the synthesis of dipicolinic acid. The synthesis of spore material 

 and the production of spore-like structure can occur independently of 

 the synthesis of dipicolinic acid. The only function that the dipicolinic 

 acid plays in the process is to produce a structure which can protect the 

 enzymes and make the spore heat-resistant. Heat resistance cannot 

 develop until after the DPA has been synthesized. This lends further 

 circumstantial evidence to the theory that dipicolinic acid is involved 

 in the formation of a complex which serves to protect the enzymes and 

 make them heat-resistant. 



References 



Brown, W. L., 1956. "The Production and Germination Requirements of Putre- 

 factive Anaerobe 3679 Spores," unpublished doctoral thesis, University of 

 Illinois. 



Church, B. D., and Halvorson, H., 1955. "Glucose Metabolism of Resting Spores of 

 Aerobic Bacilli," Bad. Proc. 41 . 



Church, B. D., and Halvorson, Harlyn, 1959. "Dependence of the Heat Resistance 

 of Bacterial Endospores on Their Dipicolinic Acid Content," Nature 183, 124. 



Collier, R., 1958. "A study of Sporogenesis in Clostridium roseum," unpublished 

 doctoral thesis, University of Illinois. 



Foster, J. W., 1959. "Dipicolinic Acid and Bacterial Spores," lecture given at 

 the University of Maryland. Sponsored by American Cyanamid Co., Chas. 

 Pfizer and Sons, and Merck and Co. 



GoUakota, K. G., and Halvorson, H. Orin, 1960. "Biochemical Changes Occurring 

 During Sporulation of Bacillus cereus. Inhibition of Sporalation by Alpha 

 Picolinic Acid," /. Bad. 79, 1. 



