FERMENTATION ORGANISMS 111 



4. Draw a conidiophore and spores. 



5. Lift out pieces of agar on which Penicillium has been 

 sown for two days. Study the mycelium it contains. Have the 

 hyphre cross walls ? Do they branch extensively ? Draw a bit 



of mycelium. 



Exercise 153. Study of Aspergillus 



This mold fungus is also of wide distribution, usually develop- 

 ing at rather high temperatures. 



Morphologically it is quite similar to Penicillium, and like- 

 wise, the conidial spore form is abundant, while the ascospore is 

 comparatively rare. Aspergillus niger is more or less common as 

 a black mold on organic substances. It forms oxalic acid in 

 considerable quantities when grown upon media containing 

 sugars. The fungus produces diastase, maltase, invertase, and 

 emulsin. 



Aspergillus oryzae is of considerable interest on account of its 

 pronounced diastatic action. It is, in fact, an important source 

 of diastase, the takadiastase of commerce. This fungus is used 

 in the preparation of rice beer, or sake, a favorite beverage in 

 Japan. The Aspergillus is used to convert the rice starch into 

 sugar; then the sugar is fermented by yeasts which find their 

 way into the mass. 



1. Examine a culture of Aspergillus and note 



a. The general appearance of the whole mass. 



b. The position and direction of the threads with, reference 



to the supporting substratum. 



Remove a small tuft of these aerial hyprue, place them in a 

 drop of 50 per cent alcohol on a slide, tease apart carefully, and 

 examine with both high and low powers. 



2. The conidiophores are the aerial branches, each of which 

 ends in an enlargement. The surface of this swollen tip gives 

 rise to numerous sterigmata, or stalk cells, which bear the spores. 

 In some species sterigmata are not formed. 



3. The spores arise in basipetal order from the sterigmata. 

 Are the spores relatively few or abundant? What is their 

 shape? color? Is the spore wall thickened? Do the spores 

 contain protoplasm ? oil ? vacuoles ? 



