ENZYMES ACTIVE IN THE INTACT SPORE 103 



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spores of Bacillus cereus; M. S. Thesis, University of Illinois. 

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of Bacillus subtilis spores in L-alanine solution. J. Gen. Microbiol. 4: 



330-338. 

 Powell, J. F. and J. R. Hunter. 1955. Spore germination in the genus 



Bacillus; the modification of germinating requirements as a result of 



preheating. J. Gen. Microbiol. 13: 59-67. 

 Powell, J. F. and J. R. Hunter. 1956. Adenosine deaminase and ribosidase 



in spores of B. cereus. Biochem. J. 62: 381-387. 

 Stewart, B. T. and H. Orin Halvorson. 1953. Studies on the spores of 



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aerobic bacteria. H. The properties of an extracted heat-stable enzyme 



Arch. Biochem. & Biophysics. 49: 168-178. 



Informal Discussion 



Mandels: I would like to make a few comments relating to the remarks 

 of Dr. Lawrence on the enzymatic activity of spores. In our studies with 

 fungus spores, we have found the intact, viable spores to possess fairly high 

 enzymatic activity — the enzymes we have worked with being invertase, an 

 atypical ascorbic acid oxidase, and a sulfhydryl oxidase. The activity of these 

 enzymes is much higher than could possibly be necessary for metabolic re- 

 quirements of the cell. Furthermore, we can completely inactivate these en- 

 zymes without impairing the metabolic activity of the cell. Thus, it is quite 

 possible that there are enzymatically active proteins in spores, and possibly 

 vegetative cells, too, that have no particular catalytic function essential to the 

 metabolism of the cell. The enzymes I have mentioned are apparently local- 

 ized on the external surface of the plasma membrane of the spore. Their pri- 

 mary function may thus be as structural proteins in the membrane. 



FiTZ- James: I should like to say a word about cleaning spores and light 

 microscopy as a criterion of cleanliness. The light microscope will detect 

 the presence of larger pieces of vegetative debris, but one really needs an 

 electron microscope to decide the purity of a spore preparation. In trying to 

 clean the spore of crystallophoric strains of B. cereus, we at first felt quite 

 satisfied from observations with the light microscope that repeated alkali and 

 water washings of spore-crystal mixtures were giving us clean spores. The 

 electron microscope, however, showed they were coated with variable amounts 

 of fibrous crystal protein, and further cleaning with acid and alkali was 

 necessary to free spores completely of crystal protein. 



Harlyn Halvorson. The enzyme content and biochemical capabilities of 

 spores indicate that they are physiologically more akin to vegetative cells than 



