768 Journal of Agricultural Research voi.xx.No. 10 



The results show that the hydrolytic power of the mycelium stored 

 at 6o° C. at the end of 73 days is somewhat more impaired than that of 

 mycelium stored at 35 and 9 for the same length of time. On the 

 other hand, the results indicate that the mycelium may be safely stored 

 for a considerable time at 9 and 35 without materially affecting the 

 enzym. 



EFFECT OF TEMPERATURE ON THE HYDROLYTIC POWER OF THE ENZYM 



It is generally understood that enzyms are more resistant to heat 

 when in the form of a powder than when in suspension. Kjeldahl (18) 

 found that the action of amylase at o° C. was very slow but increased 

 rapidly with the increase in temperature up to 6o° and at 70 became 

 insignificant. Similar results were obtained by Durandard (11), who 

 reports that the optimum temperature for the hydrolysis of rice starch 

 by an extract of Rhizopus nigricans to be 45 °. He obtained some 

 hydrolysis at io° and four times as much at 45 as at 30 . It dimin- 

 ishes rapidly toward 55 °, becoming very feeble at 6o° and nothing at 70 . 

 The writer found likewise the optimum temperature for the hydrolysis 

 of potato starch to be about 45 °, with a gradual decrease above that 

 temperature, becoming practically nothing at 6o°. Effront (12) con- 

 cludes also that the temperature has no other effect than to reduce the 

 diastatic power, and the nearer the temperature approaches 70 the 

 greater is the reduction. White (26) found that certain enzyms in dry 

 oats, among them diastase, were not injured on heating for 4K hours to 

 ioo°, but that an exposure for one hour at 130 did destroy the ferments. 



That the amylase contained in Rhizopus tritici is destroyed at a tem- 

 perature of 6o°C. is shown in the following experiments. Five-tenths gm. 

 of mycelium was extracted for 24 hours in each of two flasks containing 

 150 cc. of sterile distilled water at a temperature of 9 . The contents of 

 the flasks were then filtered, and 100 cc. were pipetted into 250-cc. flasks. 

 Both flasks were exposed for an additional 100 hours, one at a tempera- 

 ture of 6o° and one at 9 . The contents of each flask were then diluted 

 with 100 cc. of a 1 per cent starch paste and hydrolyzed for 18 hours 

 more at 40 . At 6o° and 9 the reducing sugars formed per 10 cc. of 

 solution were on an average 1 .36 and 36.36 mgm. , respectively. Although 

 a little reducing sugar was formed, it is believed that it was derived by 

 autolysis of the mycelium during the period of extraction. 



INFLUENCE OF GLUCOSE ON THE HYDROLYSIS OF STARCH 



The stimulating and retarding effect of certain substances, especially 

 those identical with or similar to the products of hydrolysis, have been 

 subjects of investigations for a long time. Hill (75) found that glucose 

 interfered with the action of maltose, and Armstrong (1) pointed out a 

 number of cases where the reaction products inhibited the action of the 



