CULTURE MEDIA FOR CULTIVATION OF MICROORGANISMS 



463 



1602. Sturtevant's Egg Yolk Yeast Agar 



Constituents: 



1. Water 1000.0 cc. 



2. Yeast (dry) 10.0 g. 



3. Peptone 10.0 g. 



4. Sodium glycero-phosphate 

 (buffer)....' 5.0 g. 



5. Agar 15.0 g. 



6. Egg yolk 

 Preparation : 



(1) Heat 10.0 g. dry yeast, 10.0 g. pep- 

 tone and 5.0 g. buffer (sodium glyc- 

 ero-phosphate) in 500.0 cc. of water 

 with flowing steam for 30 minutes. 



(2) Adjust to pH = 7.6 to 7.8. 



(3) Boil for one minute over a free 

 flame. 



(4) Filter thru paper on a perforated 

 porcelain funnel, using siliceous 

 earth to clarify. 



(5) Place 15.0 g. of shred agar in 1000.0 

 cc. distilled water and allow to stand 

 for 24 hours at room temperature. 



(6) Pour off as much of the water as 

 possible by placing a piece of cheese 

 cloth over the top of the flask. 



(7) Add as much distilled water as was 

 poured off and soak for another 24 

 hours. 



(8) Filter thru a cotton flannel cloth, 

 and wash the agar with 500.0 cc. of 

 distilled water. 



(9) Allow to drain, and squeeze the agar 

 as free from water as possible. 



(10) Add enough water to (9) so that the 

 total weight will be 515.0 g. 



(11) Dissolve the agar in the water by 

 heating. 



(12) Filter. 



(13) Mix equal parts of (4) and (12) 

 (double strength agar). 



(14) Prepare a series of flasks containing 

 200.0 cc. of water. 0.5 to 1.0% 

 neutral buffer salt may be added to 

 keep the acidity down which 

 develops on long standing. A small 

 amount of normal NaOH 2 to 3.0 cc. 

 is added. This tends to keep the 

 egg yolk suspension at the desired 

 pH. Plug the flasks with cotton and 

 protect the plug with a paper cap. 



(15) Add under aseptic conditions the 

 yolk of one egg to each sterile flask 

 of (14). Mix well. 



(16) Adjust the reaction of (13) so that 

 upon the addition of 1.0 cc. of (15) 

 to 10.0 cc. of the agar, the final pH 

 value will be about 6.8. 



(17) Tube the agar (without the addition 

 of egg yolk suspension) in 10.0 cc. 

 lots. 



(18) When desired for use add 1.0 to 2.0 

 cc. of (15) to each tube of melted 

 agar under aseptic conditions, mix 

 M'ell and slant. The agar should be 

 cooled to about 55°C. 



Sterilization: Sterilize (14); method not 

 given. Sterilize (17) by autoclaving at 

 15 pounds pressure for 15 minutes. 



Use: Isolation of organism causing 

 American foul brood, Bacillus larvae. To 

 isolate the organism, drop some infected 

 material into the water of condensation 

 and smear over the surface of the agar. 

 Author reported that best growth was 

 obtained when 0.5% glucose was added. 

 To make counts, add only 10 or 15 drops 

 of the egg yolk suspension, or 1.0 cc. of 

 the supernatant fluid of the suspension 

 to 10.0 cc. yeast extract agar containing 

 varying amounts of glucose. Mix thoroly 

 and pour in plates. Add a dilute solution 

 of fuchsin to the plates when counting. 

 This colors the colonies. 



Variants: Author added from 0.5 to 10.0% 

 glucose. 



Reference: Sturtevant (1924 p. 136). 



1603. Savini and Savini-Gastano's 



Hemoglobin Bacterial Extract 



Agar 



Same as medium 977 but agar employed 

 instead of bouillon. 



1604. Mankowski's Fungus Infusion 

 Peptone Agar 



Constituents: 



1. Fungus infusion 1000.0 cc. 



2. Agar 15 g. 



3. Peptone 10.0 g. 



4. NaCl 5.0 g. 



Preparation : 



(1) Method of preparation of Fungus 

 infusion not given. 



(2) Dissolve 2, 3 and 4 in (1). 



(3) Clarify with egg white. 



(4) The reaction is neutral. 

 Sterilization: Not specified. 



