SUGGESTED LABORATORY EXERCISES 427 



topic see Chaps. 7 and 14. In this study, the nitrogen source in the 

 media should be simple and available to as many fungi as possible. For 

 this purpose, asparagine is quite satisfactory. 



Malt extract-yeast extract agar may be used as a standard controi 

 medium, since this is an excellent natural medium for most fungi. If 

 desired, any other standard natural medium may be used as a control 

 medium. All other media used in the exercise will have the same basal 

 composition, with the carbon source as the only variable. Adjust the 

 pH of all media to approximately 6.0 before autoclaving. 



Basal Semisynthetic Medium 



Carbon source 10 g. 



Asparagine 2 g. 



KH2PO4 1 g. 



MgSOrTH.0 0.5 g. 



Fe+ + + 0.2 mg. 



Zn++ 0.2 mg. 



Mn++ 0.1 mg. 



Biotin 5 Mg 



Thiamine 100 ^g 



Distilled water to make 1 liter 



Agar (for solid media) 20 g. 



For the most accurate measure of growth, liquid media should be used, 

 so that the mycelium may be filtered off, washed, dried, and weighed. 

 However, agar media are often more satisfactory for reproduction. It is 

 suggested that this exercise be carried out on agar slants in test tubes. 



Media 



4. Same as medium 1 



5. Glucose. Media 5 to 13 will all contain the basal medium above. 



6. Sucrose 7. Sorbose 

 8. Lactose 9. Maltose 



10. Galactose 11. Starch 



12. Cellulosei 13. No sugar 



Each student should select two or more species of fungi and inoculate 

 with each fungus three tubes of each of the 10 media listed above. Incu- 

 bate at 25°C., or at room temperature. Use for inoculum spores or small 

 bits of mycelium with as little agar as possible. 



Records. The student will be responsible for taking notes or data on 

 the growth and sporulation of the fungi he selects, but he should follow 

 the form suggested by the leader of the exercise. He should also observe 

 the results of students who use other species. Records on growth may be 

 made at the end of 3 to 7 days, depending upon the fungus, while a greater 

 time should be allowed before making final records on sporulation. For 

 most purposes a record of the relative amount of growth or sporulation, 



' Use good grade of filter paper, add water, and cut to a pulp in a Waring Blendor. 



