i'K< )i)r("i'i(tN OF i:\ZNMi;s 



185 



lilti'atcs of ccrtaiii species wcic loiiiul lo 

 exeiM a niai'ked ( iTect not only upon animal 

 proteins hut also upon proteins (leiixcd iVoni 

 soybeans, peaiuit meal, and coin meal. Ac- 

 eofdinu; to Simon, .S'. (jrisf ns pcoduced pro- 

 tease in a medium containiiiii; 2 per ccMit 

 soybean meal. An acti\-e en/yme preparation 

 with a poteiK-y ecjual to liiat ot panereatin 

 was obtained; the actixity did not decrease 

 on dialysis. Casein, soybean, protein, fibrin, 

 and peptone could be used as substrat(\s. 

 The oi)timum reaction for the acti\-ity of the 

 enzyme was pll 8.2. An a(|ueous solution of 

 the enzyme was inactivated at (iO^'C in .'!() 

 minutes. Further studies on the pioduction 

 of proteolytic enzymes by xarious actino- 

 mycetes have been made by Xaeslund and 

 Deniby (1923). The formation by different 

 streptomycetes of proteolytic enzymes as 

 well as of amylolytic and iiu'erting systems 

 has l)een discussed in detail by Jensen (Table 

 4(3). See also Tytell et al. (1954). 



Bechtereva et al. (1958) studied the course 

 of accumulation of active proteolytic en- 

 zymes by iS'. violaceus and S. lavendulae. The 

 p(>riod of intensive accumulation of active 

 proteolytic enzjanes in a simple synthetic 

 medium and in a corn-extract medium was 

 found to be related to the decomposition of 

 the cells. Upon submerged fermentation in 

 media containing proteins, the release of 

 active proteolytic enzymes may accompany 

 not only decomposition of mature cells l)ut 

 also \-igorous growth oi the young healthy 

 hyphae. The concentration of the nitroge- 

 nous components in the medium greatly 

 influences the rate of decomposition of the 

 S. lavendulae mycelium and the accumula- 

 tion of active proteolytic enzymes. 



Ken net or Lal> 



Coagulation of milk by microorganisms 

 can be brought about either through the 

 action of the lactic acid formed from the 

 lacto.se or by means of an enzyme, usually- 

 designated as lab or rennet. Since the ma- 



'i"\in,K 1(1 

 ilmlidii (if (lidsldsr, inrcrldsc, anil ijiolcnse by 

 ilijft 11 III iicUiKinn/celcs (Joii.s(mi, lIKiO) 



jority of actinomycetes do not form any 

 lactic acid from lactose, the production of 

 lab can easily be established. The addition 

 of some CaClo is favorable to the coagulation 

 process. While the optimum temperature for 

 growth of the organism may be 28 or 37 °C, 

 that for enzyme action is 55 to G5°C. Heat- 

 ing to 70°C has no injurious effect, but ac- 

 tixity is destroyed at 80°C for 30 minutes. 

 I^ieske obtained an active preparation of lab 

 by precipitating a li(iuefied milk culture of 

 the organism with alcohol. The lab enzyme 

 is also produced by active cultures grown in 

 other media, such as l:)lood serum. 



The fact that certain actinon\ycetes were 

 capable of clarifying the milk without pre- 

 vious coagulation, whei'eas others brought 

 al)out coagulation followed by varying de- 

 grees of decomposition of the coagulum, sug- 

 gests the possibility that lab is an enzyme 

 distinct from th(> true proteolytic enzymes 

 (Waksman, lOlS). 



Keratinase 



Xo\al and Xickerson obtained, from a 

 cult ure ofS.fradiae, a highly potent prepara- 



