DORMANCY OF BACTERIAL ENDOSPORE 75 



1 



dormant spores is less than 0.05 or about ;r^^ of the activity 

 of corresponding vegetative cells. ' 



These findings, which have been observed by a number of 

 workers, illustrate several features of dormant endospores: 



1 . Their overall respiratory activity is negligible if not com- 

 pletely inactive; 



2. Respiratory activity is acquired prior to germination by 

 appropriate activation either by heat or by chemicals; 



3. Germination leads to more full metabolic activity. In this 

 latter case, Levinson and Hyatt^^ have shown that this can 

 be largely achieved under nutritional conditions where 

 protein biosynthesis is negligible. It is therefore clear that 

 the metabolic systems involved are pre-existent in the 

 dormant spore. 



ENZYME PATTERN OF DORMANT SPORES 



It was originally believed that dormant spores were devoid of 

 enzymic activity. This is clearly not the case. Since the discovery 

 of alanine racemase^^ and catalase^^' -^, an increasing number of 

 enzymic activities have been recognized in dormant spores. In 

 some cases, such as pyrophosphatase^^ and alanine racemase^^, 

 the enzyme content is higher in spores than in vegetative cells. 

 A similar situation exists regarding enzymic reactions demon- 

 strable in extracts of dormant spores. During the past seven 

 years there has been an exponential increase in the number of 

 enzymes recognizable in spores — suggesting that the enzyme 

 pattern of spores may closely resemble that of the sporulating 

 cell. 



Three rather broad classes of enzymes can be recognized in 

 spores: 



(a) Enzymes active in intact dormant spores; 



(b) Enzymes dormant in intact spores, but recognizable 

 following activation; 



(c) Enzymes active only in extracts of dormant spores. 



References p. 94 



