MAINTENANCE AND PRESERVATION OF CULTURES 111 



17. Liver Medium (Northern Regional Research Laboratory) 



Liver extract (commercial) 10 g 



Yeast extract 5 g 



Tryptone 10 g 



K2HPO4 2g 



Glucose 5 g 



Distilled water 1,000 ml 



pH7.4 



If stabs are desired, add 10 g of agar. Liver extract can be prepared by placing 1 lb 

 of ground beef liver in 2 liters of water and heating in flowing steam for about 3 hr 

 until the liquid assumes a yellow fluorescence. Filter through cheesecloth, place in 

 flasks, and autoclave. Keep aseptically, and use 100 ml in above formula; reduce 

 water to 900 ml. Save the solid meat, and place a few particles in each tube. 



18. Low enstein- Jensen Medium 



Commercial preparations are advised. 



19. Meat-infusion Broth 



Lean ground beef 500 g 



Distilled water 1,000 ml 



Mix thoroughly; store in refrigerator overnight. Skim off fat, strain the infusion 

 through cheesecloth, and add 



Peptone 10 g 



NaCl 5 g 



Dissolve by heating, strain through cheesecloth, and make up to volume. Adjust 

 pH to 7.4. Heat in autoclave 10 min at 15 lb, filter through paper, and adjust pH. 

 Dispense in tubes, and autoclave 20 min at 15 lb. 



20. NIH Semisolid Medium 



(National Institutes of Health) 



Meat infusion l^roth . 675 ml 



Nutrient agar 1.8 g 



Distilled water 75 ml 



KCl (1.5 g in 10 ml of water) 1 ml 



CaCh (1.5 g in 10 ml of water) 0.5 ml 



Heat to 100°C; adjust pH to 7.0, tube for stabs. 



21. Nitrobacter Medium 



(a)NaN02 10 g 



K2HPO4 r 0.5 g 



NaCl 0.3 g 



MgS04 0.5 g 



MnSO* Trace 



Fe2(S04)3 Trace 



Distilled wcder 1,000 ml 



pH7.5 



Put 100-ml portions in flasks. Autoclave. 



(6) Wash marble chips thoroughly in distilled water; place in large test tubes, 

 about one-third full; autoclave 1 hr at 15 lb. Add (a) to (b) aseptically. 



