160 HARLYN HALVORSON 



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Discussion 



Joan F. Powell 



Dr. Halvorson has described enzyme systems present in resting spores of 

 B. cereus which oxidize glucose to gluconate and pyruvate. These systems ap- 

 pear to be DPN- or TPN-dependent and it seems likely that the terminal 

 stages of the oxidation proceed through flavoprotein and cytochrome systems. 

 We found that spore extracts of B. suhtilis and B. megatherium contained 

 both free and combined flavin adenine dinucleotide (FAD) and we demon- 

 strated the presence of a diaphorase-like system in these extracts ( Spencer 

 and Powell, 1951 ) . Vegetative cells contained roughly three to four times as 

 much FAD as spores on a basis of cell dry weight. They also had a much 

 higher diaphorase activity than spores. 



Keilin and Hartree (1949) reported that although spores of B. subtilis 

 contained considerable amounts of unidentified haematin compounds, their 

 cytochrome content was only 6% of that of vegetative cells. Chaix and Ron- 

 coli (1950) observed the development from an atypical to a "classical" cyto- 

 chrome spectrum during the growth of B. subtilis. We attempted to dem- 

 onstrate the presence of a cytochrome-cytochrome oxidase system in spores 

 of B. subtilis and B. megatherium using methods depending on catalyzed 



