THE BACTERIAL ENDOSPORE 61 



Lees: I am afraid I am totally ignorant of these matters. Does 

 the spore contain structural proteins or lipoproteins, and if so 

 does this same mechanism confer stability on them? Secondly 

 does this mechanism you postulated for controlling heat 

 stability also confer resistance to lack of water in the case of the 

 spore? 



Halvorson : These abnormal spores are resistant to chemicals 

 like octyl alcohol. They are not heat resistant, and like normal 

 spores, do not show enzymic activity. We found a virus infecting 

 our spores at a very late stage of growth; it became incorporated 

 in the spore particles, and these were heat resistant. We tried 

 this with our particular spores, and found them to become 

 infected in the same way, with partial protection against heat. 

 There were few heat-resistant spores and these contained 

 dipicolinic acid. It may be that dipicolinic acid is protecting the 

 virus. 



Keynan: What might be the mechanism of the protection 

 given by dipicolinic acid to the spore? 



Halvorson: I wish I knew the answer to that. All we have so 

 far is indirect evidence that a complex is involved, but the 

 pesky complex breaks up when we rupture the spore so that 

 our hands are tied and we need some new ideas before we can 

 ask the right question and suggest the proper experiment. 



Keynan: Will a-dipicolinic acid inhibit sporulation in aerobic 

 systems? 



Halvorson: It also does the same thing with anaerobic 

 spores. Ethyl oxamate, indeed, prevents the formation of heat- 

 susceptible spores in anaerobes. 



Keynan: Does ethyl pyruvate interfere with the growth of 

 the vegetative cell? 



Halvorson: This is the only one of the ethyl esters tested 

 that had any effect on the growth of vegetative cells. However, 

 it does not stop growth altogether. It also interferes with 

 germination of spores. 



Keynan: Does it interfere with sporulation or just with 

 growth? 



