332 



CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



(3) After pouring off the last water add 

 18 liters of water to the remaining 

 washed yeast cells. 



(4) Boil in the autoclave or steamer as in 

 the preparation of meat bouillon. 



(5) Allow to stand for a suitable length 

 of time and remove the liquid from 

 the sediment or filter thru filter paper. 



(6) Add 0.3 or 0.5% lactose to the filtrate 

 or supernatant fluid. 



(7) Adjust to slightly alkaline to litmus. 

 Sterilization: Not specified. 



Use: General inexpensive culture medium. 

 Variants : The author used the medium with 



constituents of double strength, with or 



without 0.5% NaCl. 

 Reference: Gassner (1916-17 p. 311). 



1144. KorfE's Sucrose Yeast Infusion 

 Solution 



Constituents: 



1. Water 2000.0 to 3000.0 cc. 



2. Yeast 1000.0 g. 



3. Sucrose. 

 Preparation : 



(1) Mix 1000.0 g. of yeast with water and 

 decant. Continue this until the 

 liquid is colorless and does not re- 

 duce Fehling's solution. 



(2) Pour the yeast in a porcelain funnel 

 provided with a sieve plate. 



(3) Wash repeatedly with distilled 

 water. 



(4) Place the yeast in a large flask with 

 2 or 3 liters of water and boil for 

 30 minutes. 



(5) Allow to settle. 



(6) Filter. 



(7) Boil the filtrate once more. 



(8) Filter. 



(9) Determine the specific weight and 

 dilute to a suitable specific weight 

 (1.0033 g.). 



(10) Dissolve 1000.0 g. of white sugar 

 candy in 500.0 g. distilled water by 

 heating on the water bath. 



(11) Filter while hot in the hot water 

 funnel into a large porcelain dish. 



(12) Add 2 liters of warm absolute alco- 

 hol, stirring continually. 



(13) Pour the cool alcohol from the sugar 

 and wash the sugar with absolute 

 alcohol and then with ether. 



(14) Dry at 60°C. until all traces of damp- 



ness of alcohol or ether have dis- 

 appeared. 



(15) Prepare a 10.0% solution of (14) in 

 distilled water. 



(16) Mix about 10.0% of (15) with 10.0% 

 of (9). 



(17) Distribute in 150.0 cc. lots in fer- 

 mentation flasks. 



Sterilization: Sterilize in streaming steam. 



Use: To study fermentation by yeast. 

 Waterman used a similar medium to 

 study the inversion of sucrose by bacteria. 



Variants : 



(a) Syr(§e prepared a similar medium as 

 follows: 



(1) Wash brewers yeast in a decanta- 

 tion funnel with distilled water 

 until the wash water, to which 

 some yeast has been added, boiled 

 and filtered, will give no reaction 

 with Fehling's solution. 



(2) Boil 1000.0 g. of the washed yeast 

 with 2 liters distilled water for 

 2 hours. 



(3) Filter. 



(4) Boil the filtrate once more. 



(5) Filter. 



(6) Estimate the nitrogen content by 

 Kjeldahl's method and dilute so 

 that the nitrogen content is 

 0.0448%. 



(7) Weigh 100.0 g. of dried sucrose, 

 prepared as indicated above. 

 Step (10) thru (14) in a liter volu- 

 metric flask. 



(8) Pipette 100.0 cc. of (6) in the flask 

 with the sugar. 



(9) Add distilled water to make 

 1.0 liter volume. 



(10) Distribute into 150.0 cc. lots, plug 

 with cotton and gum, and sterilize 

 in streaming steam. 



(11) Shake often during cooling to satu- 

 rate the medium with air. 



(b) Henneberg added 10.0% sucrose to a 

 1.0 to 15.0% yeast infusion solution. 

 The reaction was made neutral with 

 soda. The medium was used for the 

 cultivation of lactic acid bacteria. 



(c) Will added 6.0% sucrose to yeast 

 water (preparation not given). 



(d) Waterman added 4.0% sucrose to 

 yeast water (preparation not given) 

 to study the inversion of sucrose by 



