CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



805 



(7) Add any desired nutrient salts. 



(8) Allow to stand. A gel forms. 

 Sterilization: See steps (4) and (5) above. 

 Use: Synthetic culture medium. 



Added nutrients: The author added a con- 

 centrated sterile solution of any desired 

 salts. 



Variants : The author used HCl, H2SO4, and 

 H3PO4 alone or in mixtures instead 

 of HCl. 



Reference: Doryland (1916 p. 144). 



2471. Sleskin's Ammonium Sulphate 

 Silicate Jelly 



Constituents: 



1. Water 1000.0 cc. 



2. (NH4)2S04 4.0 g. 



3. MgS04 0-5 g- 



4. Potassium phosphate. 1.0 g. 



5. CaCU trace 



6. NaoCOa 6.0 to 9.0 g. 



7. Water glass 



8. HCl 

 Preparation: 



(1) Pour 1 part diluted HCl (HCl with 

 specific gravity of 1.17 one part with 

 one part water) into 3 parts diluted 

 water glass (specific gravity 1.08). 



(2) Dialyze in running water until free 

 from chlorine. 



(3) Store sterile in a water free place 



until ready for use. 



(4) Evaporate (3) in a platinum dish 

 under a flame to a specific gravity of 

 1.02 (acid content 3.4%) or better 

 until the fluid has become quite a 

 thick liquid, about 5 the volume and 

 needle like crystals can be seen 

 swimming in different depths of the 

 liquid. This is best carried out by 

 measuring about s or 5 of the 

 volume of the liquid making a mark 

 on the wall of the container and then 

 evaporate by boiling to this mark. 



(5) Dissolve (NH4)2S04 and MgS04 in 

 the least amount of water possible. 



(6) Dissolve potassium phosphate and 

 Na-jCOs in least amount of water 

 possible. 



(7) Prepare a very dilute solution of 

 CaClo. 



(8) Store sterile (5), (6) and (7) until 

 ready for use. 



(9) These salts may be mixed with 



various amounts of silicic acid. 

 1.15% to 1.45% salts give a fairly 

 good nutrient jelly. If 2 to 3.0% 

 of mineral salt be added solidifica- 

 tion will take place much more 

 rapidly. Instead of dissolving the 

 salts in water and then adding the 

 salt solution to the silicic acid, add 

 the corresponding amount of water 

 as the amount of mineral salts you 

 desire in the medium to (4). 



(10) Pour the sterilized (5) and (6) into 

 (9) and mix well and finally a few 

 drops of sterile weak CaCli solution 

 until the mixture becomes rather 

 vicous. 



(11) The liquid then is poured into sterile 

 Petri dishes (it may be inoculated in 

 liquid state) and allowed to stand 

 at room temperature to solidify 

 (requires several hours). 



Sterilization: Method not specified. 

 Use: Cultivation of nitrifying organisms. 

 Variants : 



(a) Burri and Stutzer prepared a similar 

 medium as follows: 



(1) Mix equal volumes of waterglass 

 (sp. gr. 1.05) and HCl (sp. wt. 

 1.10). 



(2) Dialyze in running tap water for 

 24 hours. 



(3) Dialyze in distilled water for 4 

 days, changing the water three 

 times a day. 



(4) Evaporate 600.0 cc. of (3) to 

 150.0 to 200.0 cc. by boiling over 

 a free flame. 



(5) Transfer to sterile flask that is 

 marked at 100.0 cc. Plug with 

 cotton or close with asbestos and 

 continue the evaporation until the 

 100.0 cc. volume mark is reached. 



(6) Dissolve 10.0 g. KH2PO4, 5.0 g. 

 MgS04, 10.0 g. NaCl and a trace of 

 CaClo in 1000.0 cc. water. 



(7) Prepare a 10.0% (NH4)2S04 solu- 

 tion. 



(8) Prepare a soda solution (strength 

 not given). 



(9) Sterilize (6), (7), (8), and (9), 

 separately. (Method not given.) 



(10) Add 10.0 cc. sterile (6) to sterile 

 (5), and on the other side of the 

 flask add sterile ammonia sul- 



