186 



THE ACTINOMYCETES, Vol. I 



tion of keratinase that digested hoofmeal, 

 wool, and feathers. Xo^'al (1957) made a 

 comprehensive study of this preparation. 



Three strains of S. Jradiae were isolated 

 and found capable of rapidly soluhilizing 80 

 to 90 per cent of native keratin. One of these, 

 8. fradiae 3739, was isolated as the most 

 active keratin-digesting strain and was used 

 for the preparation of the enzyme. Signif- 

 icant stimulation in the digestion of wool 

 by this culture was obtained by increasing 

 the Ca++ and/or Mg++ concentration of 

 the media. Approximately two-thirds of the 

 cystine of the digested wool accumulated as 

 soluble sulfhydryl compounds in the culture 

 broth during the digestion. The sulfhydryl 

 material was very stable to aeration, heating, 

 and acidification but was substantially de- 

 stroyed by addition of organic solvents to 

 the acidified broth in the presence of light. 

 Neither cysteine nor sulfide was detectable 

 in the culture broth during or after the ac- 

 tive digestion of wool. Most (75 per cent) of 

 the nitrogen of the solubilized wool was ac- 

 cumulated in the form of ammonia. 



The cell-free culture broth of *S. fradiae 

 3739 was capable of enzymatically digesting 

 keratins and casein. The enzymes that 

 caused both of these digestions were similar 

 in their optimal activity at about pH 9 and 

 in their nonsensitivity to sulfhydryl rea- 

 gents. Magnesium appeared to be the metal 

 refiuired for the digestion of wool by the 

 culture broths. 



The culture broths of »S. Jradiae were cap- 

 able of solubilizing a maximum of 10 to 20 

 per cent of several native keratinaceous sub- 

 stances; trypsin and papain could solubilize, 

 at the most, al)out half as much (5 to 10 

 per cent) of each of the same keratins. By 

 ammonium sulfate precipitation, a product 

 was obtained that had about Hi times as 

 much wool-digesting ac^tivity per niilligi'am 

 of protein as did the culture broth. 



Urease 



Various actinomycetes, like S. griseus, 

 were found (Simon) to produce urease. This 

 enzyme was found also in cultures grown in 

 urea-free media; hence it is not adaptive in 

 nature. It was suggested that urea may be 

 produced by the organism from guanidine 

 by the action of guanidase. 



Deguanidase 



S. griseus was found by Roche et al. to 

 produce a system of deguanidases that are 

 active at pH 7.5 upon different monosubsti- 

 tuted guanidines. This system comprises a 

 mixture of enzymes different from arginase. 

 Its diffusion in the medium can bring about 

 the destruction of streptomycin. 



Chitinase 



Nearly all streptomyces are capable of 

 producing an enzyme that has the capacity 

 to hydrolyze chitin. Jeuniaux reported that 

 this enzyme is formed in a simple synthetic 

 medium containing chitin as the only source 

 of carbon and nitrogen. The enzyme is also 

 produced in the absence of chitin; the pres- 

 ence of chitin in the medium was not es- 

 sential for, although it favored, formation of 

 the enzyme. The presence of glucose tended 

 to repress the formation of chitinase. The 

 enzyme was found to be rather unstable in 

 culture filtrates, but the presence of chitin 

 tended to stabilize it. 



Bucherer has shown that ^'arious species 

 of Streptomyces, notably *S'. griseolus, S. ex- 

 foUatus, S. fradiae, S. aureus, and S. griseus 

 are able to break down chitin. According to 

 Schmidt-Lange and Bucherer, both patho- 

 genic and saprophytic actinomycetes are 

 capable of producing the enzyme chitinase. 



Yamaguchi (1957) found that different 

 species of streptomyces, such as S. fradiae, 

 ha^'e the capacity to produce a powerful 

 cuticle (of pig Ascaris) digestive substance 



