SPLITTING OF CARBOHYDRATES INTO ALCOHOL 171 



stance might be used for making solid synthetic media 

 if it could be freed in some way from all traces of food 

 materials. This he hoped to accomplish by allowing 

 the agar to ferment spontaneously upon the addition of 

 water. 



In order that agar may not support microbial growth 

 it must be allowed to ferment over a long period of time to 

 exhaust every possible trace of food. 



7. State your results in full, draw any conclusions that 

 follow and point out the practical applications that may 

 be made. 



REFERENCES 



MARSHALL: Microbiology, pp. 89-93, 98-100. 



FISCHER, A.: Structure and Functions of Bacteria, p. 115. 



EXERCISE 6. TO DEMONSTRATE THE SPLITTING OF 

 CARBOHYDRATES INTO ALCOHOL AND CO 2 



Apparatus. Clean 375 c.c. Erlenmeyer flask fitted with 

 one-hole rubber stopper containing a bent glass tube plugged 

 at the end with cotton; two calcium chloride tubes; potash 

 bulb ; calcium chloride (small granules) ; potassium hydrox- 

 ide solution (1 part KOH, 2 parts H 2 0); rubber tubing for 

 connecting up apparatus; 400 c.c. fractional distillation 

 flask; thermometer; 250 c.c. 5% saccharose bouillon. 



Culture. Sacch. cerevisice. 



Method. 1. Place the saccharose broth in the 375 c.c. 

 flask, insert the rubber stopper and sterilize by the discon- 

 tinuous method. 



2. When sterile, inoculate with the yeast and connect 

 the flask in " train " with a CaCk tube (to remove moisture) 

 a tared potash bulb (to take up 62) and a second CaCl2 

 tube. 



3. Place at 25 to 30 C. and allow to stand until no more 

 gas evolves (about two weeks) . 



4. Test quantitatively for alcohol (distill off over 10 c.c. 



