154 



THE ACTINOMYCETES, Vol. I 



LEGEND 

 [J PROLINE 



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Figure 72. Nitrogen l)alance of &. griseus fermentation (Reproduced from: Woodn.ff, H. B. aiul 

 Ruger, M. J. Bacteriol. 56: 319, 1948). 



lation of ammonia and nitrate in the soil. 

 After 120 days, 35 to 40 per cent of its nitro- 

 gen was transformed into nitrate. The addi- 

 tion of keratin produced little or no increase 

 in the number of bacterial colonies on agar 

 platings, but markedly increased the number 

 of actinomycete colonies. Two actinomycete 

 strains were isolated and foinid capable of 

 thriving on keratin in pure cultiu'e; they de- 

 composed this substance with the formation 

 of ammonia. One of the strains could be 

 recognized as *S. citreus. The other strain was 

 not named, but corresponded closely to the 

 description of Waksman's Streptomyccs 145. 

 The presence of keratinolytic actinomycetes 

 belonging to the genus Strcptomyccs in the 

 soil has been demonstrated by various other 

 investigators (Piechowska, Hirschmann et 

 al). 



Detailed studies of the decomposition of 

 hoof meal, horn meal, leathers, and similar 

 materials were made by Xoval and Nicker- 

 son and Xoval (Table 32). These investiga- 

 tors succeeded in isolating an enzj^me prep- 

 aration (keratinase) fi-om a culture of S. 

 fradiae, as is shown in Chapter 11. 



will develop (Karling, Claertner, Rothwell). 

 The mechanism of keratin destruction by 

 these organisms has not been determined. 



Jensen (1930) added to moist soil, keratin 

 prepared from horn meal and allowed it to 

 decompose. The process of keratin dcH-om- 

 position was slow; it led to a steady accumu- 



1 



