112 G, G. KRISHNA MURTY 



Murrell, Church or us in the spores actively oxidizing glucose. It is evident 

 that some of the spores have undergone a change without a simultaneous 

 loss in heat stability. The spore is also relatively rich in calcium. The above 

 findings stimulate us to speculate that the dipicolinic acid is present in the 

 spore in the form of a polymer and that the polymer produces during its 

 formation an inclusion complex with the enzyme, thus protecting it from 

 heat injury, in a manner similar to the inclusion complexes described by 

 Schlenk and coworkers (1950, 1955). Upon germination or by other means 

 of releasing dipicolinic acid from the polymer, the enzvmes are released so 

 that they become active and heat sensitive. The first phase of germination 

 would then consist of depolymerization of such a complex — a view also 

 shared by Powell, Strange and coworkers (1956). Such a view would also 

 probably explain the failure of most enzyme inhibitors to prevent germination 

 of the spores, and also the ability of aerobic spores to germinate under 

 anaerobic conditions. 



The activation of the oxidative enzymes may then, in all probability, be 

 compared to partial germination of the spore, consisting in a partial release 

 of dipicolinic acid resulting in activation of only a part of the enzymes asso- 

 ciated with growth. It is conceivable that the amount of enzyme so activated 

 is such a small part of the total enzymes of the spore that enough is left to 

 enable the spore to grow upon germination. 



There was a time when ungerminated spores were believed not to contain 

 any enzymes, but the presence of active enzymes in ungerminated spores is 

 now beyond any doubt. One may perhaps venture to state that in all prob- 

 ability the ungerminated spore contains most of the enzymes found in the 

 homologous vegetative forms. It is not too much to hope that with improved 

 techniques many more active enzymes may be demonstrated in the ungermi- 

 nated spore in the years to come. A study of the biochemical changes in- 

 volved in early phases of germination or the late phases of sporulation may 

 one day provide the answer to the interesting problem of the dormancy and 

 heat stability of the bacterial spore. 



References 



Church, B. D. and H. Halvorson. 1955. Glucose metabolism by resting 



spores of aerobic bacilli. Bact. Proc. 41. 

 Church, B. D. and H, Halvorson. 1956. Effect of heating and aging on 



germination and glucose oxidation by spores of aerobic bacilli. Bact. 



Proc. 45. 

 Harrell, W. K. 1956. Studies on dipicolinic acid in spores on Bacillus cereus 



var, terminalis. Bact. Proc. 44. 

 Murrell, W. G. 1955. The bacterial endospore. Monograph published by the 



University of Sydney, Australia. 



