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Informal Discussion 



Pow^ELL: We would like to add to the list of non-oxidative enzymes pres- 

 ent in spore extracts a as-diaminopimelic acid ( DAP I decarboxylase which 

 we have demonstrated in spores of B. sphaericus (Powell and Strange, 1957). 

 The enzyme is heat-stable in intact resting spores but becomes heat-labile 

 during germination or mechanical disintegration. The DAP decarboxylase 

 activity of vegetative cells of B. sphaericus is very much greater than that 

 of spores but is completely heat-labile in intact cells. 



I find the work that Dr. Krask has reported extremely interesting, es- 

 pecially in view of the implication that the attack of lytic systems on the 

 spore coat, splitting off peptide or breaking down polymerized phosphate, 

 may bring about the first stages of the germination process. One of the 

 most interesting properties of the intact resting spore is its resistance to 

 enzymes. I mentioned earlier the work of Douglas who is studying the elec- 

 trophoretic behaviour of resting spores before and after treatment with var- 

 ious enzymes in an attempt to get some information about their surface 

 structure. He finds small changes in the electrophoretic behaviour of rest- 

 ing spores after treatment with certain enzymes e.g. lysozyme ( Douglas and 

 Parker, 1957) ; but none of the enzymes tested produced the characteristic 

 cytological changes which occur during germination. We have recently de- 

 scribed (Powell and Strange, 1956) a lysozyme-like intra-cellular lytic sys- 

 tem which appears in sporulating cells and spores, and we have suggested 

 that the activation of this system may bring about the first stages of the 

 germination process. When resting spores are incubated with partially puri- 

 fied highly active preparations of this lytic enzyme, however, no germina- 

 tion occurs (Powell, unpublished). I would suggest that this may mean that 



