CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



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(b) Lohnis used 50.0 g. urea and 0.5 g. 

 K2HPO4 in the basic solution, and 

 added 0.5 to 1.0% ammonium or cal- 

 cium malate, or calcium citrate or 

 tartrate. 



(c) Percival used 2.5% KH2PO4 and 5.0% 

 urea and added 1.0% sodium acetate. 



References: Beijerinck (1901 p. 37), Lohnis 

 (1913 p. 108), Percival (1920 p. 225). 



489. Waksman's Basal Urea Salt Solution 



Constituents: 



1. Water 1000.0 cc. 



2. Glycerol 30.0 g. 



3. K2HPO4 1.0 g. 



4. KCl 0.5 g. 



5. MgS04 0.5 g. 



6. FeS04 0.01 g. 



7. Urea 5.0 g. 



Preparation : 



(1) Dissolve 2, 3, 4, 5, 6 and 7 in 1. 



(2) Add 2.0 g. of one of the added nu- 

 trients. 



(3) Tube in 10 to 12 cc. quantities. 

 Sterilization: Sterilize at 15 pounds for 



15 minutes. 

 Use: To study metabolism of Actinomij- 



cetes. 

 Added nutrients: Waksman added 2.0 g. 

 of one of the following nitrogen sources: 

 NaN03 (NH4).S04 



NaN02 (NH4)2C03 



Reference: Waksman (1920 p. 3). 



490. 



Christensen's Basal Urea Salt 

 Solution 



Constituents: 



1. Distilled water 1000.0 cc. 



2. Urea 20.0 g. 



3. K2HPO4 (1.0% soln.) 20.0 cc. 



4. CaCOa 



5. MgS04 small amount 



6. FeS04 small amount 



Preparation : 



(1) Prepare a 1.0% solution of K2HPO4. 



(2) Add 2.0 g. of urea (Kahlbaum's I), 

 2.0 cc. of (1), some CaCOa, and very 

 small quantities of MgS04 and FeS04 

 (amount not specified) to 1000.0 cc. 

 distilled water. 



(3) Add one of the added nutrients. 



(4) Distribute into 450.0 cc. Erlenmeyer 

 flasks. 



(5) Inoculate with a little soil infusion. 



Sterilization: Not specified. 



Use: To study urea decomposition by soil 

 forms. Ammonia formation was appar- 

 ent after 14 days when humus was added 

 and after 5 days with glucose. If humua 

 or glucose were not added, there was 

 apparently no ammonia formation. 



Added nutrients: One of the following ma- 

 terials were added: 



(a) Humus acid small amount. Add 

 sufficient dilute NaOH to keep the 

 humus acid in solution. 



(b) Potassium salt of humus acid 2.0%. 



(c) Glucose 1.0%. 



(d) "Buchenrohhumas" 0.1%. 



(e) Xylose 1.0%. 



(f) Sodium formate 0.2%. 



(g) Meat extract 2.0%. 



(h) Potassium humate 0.1% (see (8) 



below), 

 (i) Humin 0.2% (see (10) below). 

 Materials in (h) and (i) prepared as 

 follows: 



(1) Dissolve 300.0 g. saccharose in 

 420.0 cc. water. 



(2) Add 15.0 g. concentrated H2SO4 

 to (1). 



(3) Place on a boiling water bath for 

 7 or 8 hours, adding the water lost 

 by evaporation. 



(4) After completing the heating a 

 voluminous sediment forms at the 

 bottom. 



(5) Filter and carefully wash. 



(6) Treat the precipitate with an 

 excess of 5.0% KOH solution. A 

 portion of the humus acid is dis- 

 solved. The humin does not 

 dissolve. 



(7) Filter. 



(8) Utilize the filtrate to prepare a 

 neutral potassium humate (method 

 not given). 



(9) Wash the precipitate to remove all 

 traces of humus acid. 



(10) Dry (9) and pulverize humin. 

 Reference: Christensen (1910 pp. 340, 348). 



491. Fremlin's Urea Solution 



Constituents : 



1. Water 1000.0 cc. 



2. (NH4)2S04 1.0 g. 



3. Potassium phosphate . 1.0 g. 



