744 



CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



(10) Steam for 30 to 45 minutes, and 

 filter. 



(11) Tube in sterile tubes. 



(12) Steam once for 15 to 20 minutes, 

 (d) Burger made bacterial counts of 



water on a medium prepared as 

 follows: 



(1) Dissolve 10.0 g. Liebig's meat ex- 

 tract, 10.0 g. Witte's Rostock pep- 

 tone and 5.0 g. NaCl in 900.0 cc. 

 distilled water by heating in the 

 steamer (requires about one hour). 



(2) Allow (1) to cool. 



(3) Add 100.0 g. gelatin to the non- 

 filtered nutrient medium. 



(4) Allow to soak for an hour or to 

 stand in the ice box over night. 



(5) Neutralize with N/1 NaOH to 

 litmus. Shake well after each 

 addition of NaOH. 



(6) Dissolve the gelatin in the steamer 

 requiring about 30 minutes. 



(7) Make alkaline by the addition of 

 1.0 g. crystalline soda. 



(8) Cool to about 40 or 50°C. 



(9) Dissolve 1.5 g. of egg albumin in 

 25.0 cc. of luke warm water and 

 add to (8). Shake thoroly. 



(10) Boil in the steamer for about 

 30 minutes. 



(11) Filter hot, thru sterile paper at 

 room temperature of 50 or 60°C. 

 This may be carried out in the 

 steamer after the flame has been 

 removed. May allow to filter 

 over night. 



(12) Distribute in sterile flasks in 

 100.0 cc. lots or in 10.0 cc. lots in 

 sterile tubes under aseptic con- 

 ditions. 



(13) Sterilize in the steamer for about 

 20 minutes and cool quickly in 

 cold water. 



(e) Burger also prepared media in the 

 same manner as indicated above using 

 the following amounts of constit- 

 uents. Using these media, the water 

 under investigation may be added 

 directly to the sterile gelatin. 



1. Distilled water. . 800.0 cc. 750.0 cc, 



2. Meat extract 



(Liebig's) 20.0 g. 25.0 g. 



3. Peptone (Witte 



Rostock) 20.0 g. 25.0 g. 



4. NaCl 10.0 g. 12.5 g. 



5. Gelatin 200.0 g. 250.0 g. 



6. Soda (see step 



(7) above) 2.0 g. 2.5 g. 



(f) Meier used the following medium for 

 bacterial counts of milk: 



(1) Dissolve 125.0 g. gelatin, 10.0 g. 

 Liebig's meat e.xtract, 10.0 g. 

 Witte's (siccum) peptone, and 

 5.0 g. NaCl in 1000.0 cc. water. 



(2) Neutralize to litmus and then 

 add 10.0 cc. N/1 soda solution per 

 liter medium. 



(3) Sterilization not specified. 



(g) Besson prepared the medium as 

 follows: 



(1) Dissolve 5.0 g. Liebig's meat ex- 

 tract in 1000.0 cc. of water. 



(2) Dissolve 100.0 g. gelatin in (1). 



(3) Boil for 3 minutes. 



(4) Neutralize. 



(5) Heat at 115° for 5 minutes. 



(6) Filter thru paper, in the autoclave 

 or use a hot water funnel. 



(7) Tube. 



(8) Sterilize at 110° for 20 minutes, 

 (h) Wolf and Shunk reported that a 



greater pH range may be obtained 

 by adjustment of reaction after steri- 

 lization before solidification using a 

 medium prepared as follows: 



(1) Dissolve 100.0 to 150.0 g. gelatin, 

 3.0 g. Liebig's beef extract, 10.0 g. 

 Peptone (Armour's) and 5.0 g. 

 NaCl in 1000.0 cc. of water by 

 heating in autoclave. 



(2) Flask. 



(3) Sterilize at 10 pounds for 15 

 minutes. 



(4) Cool to about 40 °C. 



(5) With sterile pipette, pipette 

 10.0 cc. quantities into sterile test 

 tubes and add appropriate quan- 

 tities of strong acid or alkali 

 to give the desired reaction. 

 (Authors used HCl sp. gr. 1.20 or 

 39.11% and NaOH, sp. gr. 1.226 or 

 approximately 20.0%.) 



(6) Mix the tube thoroly and cool. 

 Do not sterilize. 



(i) Giltner prepared the medium as 

 follows: 



(1) Add 150.0 g. gelatin to a liter of 

 tap water and heat on a water bath 

 until solution is complete. 



(2) Cool down to 60 °C. 



