CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



811 



(10) It may be necessary to add more 

 sterile (1) to the block after steri- 

 lization. 



Sterilization: Sterilize at 120°C. in the 

 autoclave. Take care that the solution 

 never gets on top of the block. 

 Use: Cultivation of nitrifying organisms. 

 Reference: Omelianski (1899 p. 653). 



2481. Omelianski's Nitrite Gypsum Block 

 (Smith) 



Constituents : 



1 Distilled water 1000.0 cc. 



2. MgCO3(1.0%) 10.0 g. 



3. Gypsum 100 0^. 



4. MgSO. 0-3g- 



5. FeSO. 0-4g- 



6. NaCl 0-5g- 



7. K2HPO4 O-^S- 



8. Na^CO, ll^- 



9. NaNOi (Merck) 1-0 g- 



Preparation: 



(1) Dissolve 2, 3, 4, 5, 1.0 g. of fused 

 NaiCOa and 1.0 g. of Merck's NaNOa 

 in 1. 



(2) Uniformly mix 1.0% MgC03 with 

 gypsum and water added to it until 

 it becomes the consistency of sour 

 cream. 



(3) Pour upon a plate glass and spread 

 out. 



(4) When the mass assumes a dougby 

 consistency, cut into circular discs 

 for Petri dishes and into strips for 

 test tubes. 



(5) When the blocks have hardened, pry 

 loose from the plate glass. 



(6) Place in Petri dishes or in test tubes. 



(7) Add sterile (1) to sterile (7) until 

 the block is half immersed. Do not 

 wet the inoculated surface. 



Sterilization: Sterilize (6) in the autoclave. 



Method of sterilization of (1) not given. 

 Use: General synthetic culture medium. 

 Reference: Smith (1905 p. 199). 



2482. Omelianski's Mannitol Gypsum Block 

 (Percival) 



Constituents : 

 1. Water 



2 Gypsum (plaster of Paris) 

 3. K,HP04 0.05 g. 



4. NaCl 005 g- 



5. Mannitol 2.0 g. 



Preparation : 



(1) Mix water and Gypsum (plaster 

 Paris) to the consistency of cream 

 (about 8 volumes of gypsum powder 

 to 3.0 cc. water). 



(2) Pour on a plate of glass in a layer of 

 1 inch thicK. 



(3) Before the mixture has set cut into 

 narrow strips 3 inches long by 0.5 

 to 0.75 inches broad, or into circular 

 pieces. 



(4) Dissolve 0.5 g. K2HPO4, 0.5 g. NaCi, 

 and 2.0 g. mannitol in 100.0 cc. water. 



(5) Add 5.0 cc. of (4) to test tubes, and 

 place a strip of gypsum in each tube 

 or pour a few cc. of (4) into a Petri 

 dish, and place a circular piece of (3) 

 in the plate. 



Sterilization: Not specified. 

 Use: Cultivation of Azotobacter. 

 Reference: Percival (1920 p. 181). 



2483. MakrinofE's Leaf Infusion Gypsum 

 Block 



Constituents : 



1. Distilled water 1000.0 cc. 



2 Dry leaves 20.0 g. 



3. NaCl 2.0g. 



4. K0HPO4 10 g. 



5. MgS04 0.5 g. 



6. FeS04 0.4g. 



7. Gypsum 300.0 g. 



8. MgCOa 30.0g. 



9. MgNH4P04 3.0 g. 



Preparation : 



(1) Rub dry leaves until they are quite 

 fine. 



(2) Add 2.0% of (1) to distilled water 

 and heat in the autoclave for 15 min- 

 utes at 115°C., or in streaming steam 

 for an hour. 



(3) Filter. 



(4) To one liter of the filtrate add 2.0 g. 

 NaCl, 1.0 g. K2HPO4, 0.5 g. MgS04 

 and 0.4 g. FeS04. 



(5) To prepare plates mix 300.0 g. gyp- 

 sum, 30.0 g. MgCOs and 3.0 g. 

 MgNH4P04 thoroly. 



(6) Add (4) to (5) until a homogeneous 

 half liquid mass is formed. 



