Feb. xs, 1921 



Amylase of Rhizopus tritici 



111 



REMOVAL OF AMYLASE BY FILTERING 



The enzym powder was extracted for 24 hours in sterile distilled water. 

 The contents of one set of flasks was filtered through absorbent cotton, 

 which removed the fragments of mycelium, and the others were filtered 

 through four thicknesses of No. 1 Whatman chemically prepared filter 

 paper. A quantity of this filtered extract was then mixed with an equal 

 volume of a 1 per cent starch paste solution and hydrolyzed for 18 hours 

 at 40 C. At the close of the period of hydrolysis the reducing sugars 

 were determined in the usual way. The average of several parallel 

 experiments showed that when filtered through cotton, 172.51 mgm. 

 reducing sugars were formed in 100 cc. of solution but that only 129.32 

 mgm. were formed when filtered through filter paper. 



INFLUENCE OF TEMPERATURE AT WHICH MYCELIUM IS GROWN ON ITS 

 POWER OF HYDROLYSIS 



The investigations of the writer and others have shown that the 

 optimum temperature for the activity of amylase is about 45 ° C. and 

 that activity is reduced by higher and lower temperatures. Since these 

 results, however, were obtained from mycelium grown at one tempera- 

 ture, the question was naturally suggested whether the temperature at 

 which it was grown did not influence the amount of amylase produced. 

 The mycelium was grown on sweet potato bouillon in 2-liter Krlenmeyer 

 flasks. One set of flasks was incubated at 9 , one at 29 , and one at 40 . 

 At the close of the incubation period (10 days) the mycelium was removed 

 from the flasks and treated with acetone and ether in the usual way. 

 The mycelium from the flasks held at the same temperature was made 

 into a compound sample and stored at 9 until used. 



The hydrolytic power of the enzym was determined by the use of 0.25 

 gm. of powder in all tests but two. With the smaller amount of enzym 

 powder hydrolysis was carried out with 50 cc. of a 0.5 per cent starch 

 paste solution; with all others 100 cc. were used. The time of hydrolysis 

 was 18 hours at 40 . At the close of the experiment, the enzym was inac- 

 tivated by steaming for 10 minutes. The results are given in Table XII. 



Table XII. — Results of hydrolysis of starch by mycelium grown at different temperatures 



The results show a very striking influence of the temperature on the 

 production of amylase. A temperature of 40 C. represents about the 

 maximum temperature for growth and 9 the minimum, while a good 



