332 



THE ACTINOMYCETES, Vol. II 



This medium is usually known as Bennett's 

 agar. 



31. Glucose-yeast-malt agar: 



Glucose 4.0 gm 



Yeast extract 4.0 gm 



Malt extract 10.0 gm 



Agar 20.0 gm 



Distilled water 1000.0 ml 



pH 7.3 



32. Dextrin-casein digest agar: 



Dextrin 10.0 gm 



Yc-ist extract 1 .0 gm 



Beef extract 1.0 gm 



( 'asein digest ( X-Z-Amine A) . 2.0 gm 



CoCl 2 -7H,0 0.02 gm 



Agar 20.0 gm 



Distilled water 1000.0 ml 



Adjust to pH 7.3 

 This medium is often known as Hickey and 

 Tresner's agar. 

 34- Oatmeal agar: 



Rolled oats 20 to 65 gm 



Tap water 1000.0 ml 



Cook to thin gruel in double boiler, filter 

 through several layers of cheesecloth, and 

 make up to a liter while still hot. Add 18 to 

 20 gm agar. Adjust to pH 7.2 with NaOH. 

 34- Tomato paste-oatmeal agar: 



Heinz baby oatmeal food. . . . 20.0 gm 



Tomato paste 20.0 gm 



Tap water 500.0 ml 



Add these two ingredients to the 500 ml of 

 boiling tap water. Do not adjust pH. 



Difco agar 15.0 gm 



Tap water 500.0 ml 



Melt by steaming at 100°C for 15 to 20 min. 

 Do not adjust pH. Mix the two solutions, 

 steam at L00°C for 10 min, dispense, and 

 sterilize for 15 min at 121 °(\ 

 35. Soil extract agar: 



Beef extract 3.0 gm 



Peptone 5.0 gm 



Agar 15.0 gm 



Soil extract 1000. ml 



pH 7.0 



The soil extract is prepared by treating 1 kg 

 garden soil with 2.5 liters of tap water for 1 

 hour in autoclave at 15 lb pressure. Filter 

 hot. Add talc for clarification if necessary. 

 .;'/. Carbon nutrition medium: 



Carbon source 10.0 gm 



(NH 4 ) 2 S0 4 2.04 gm 



KH 2 P0 4 2.38 gm 



K,HP0 4 5 . 65 gm 



MgSCV7H,0 1.00 gm 



CuS0 4 -5H 2 0.0064 gm 



FeS0 4 -7H,0 0.001 gm 



MnCl 2 -4H 2 0.0070 gm 



ZnS0 4 -7H 2 0.0015 gm 



Agar 15.0 gm 



Distilled water 1000.0 ml 



Some carbon compounds may have to be 

 sterilized separately either by filtration or 

 by heating in aqueous solution. This me- 

 dium was used by Pridham and Gottlieb 

 (1948), and has found general application 

 in the study of utilization by actinomycetes 

 of different carbon sources (Fig. 66). 



37. Medium for nitrate reduction: 



Peptone 5.0 gm 



Meat extract 3.0 gm 



KN0 3 1.0 gm 



Distilled water 1000.0 ml 



pH 7.0 



38. Medium for hydrogen sulfide production: 

 Peptone-iron agar (Difco) . . 36.0 gm 



Yeast extract 1.0 gm 



Distilled water 1000.0 ml 



39. ( 'ellulose medium: 



Filter paper saturated with synthetic 

 solution, free from other carbon sources. 



40. Potato plug: 



Plugs of potatoes of desirable size and 

 shape; distilled water added and steri- 

 lized. 

 The importance of the variety and health of 

 potato has been discussed by Grein and 

 Kiister (1955). 

 ', / . Milk or litmus milk: 



Skim milk powder is used. Litmus or 

 brom-cresol may be added. 



