An Improved Medium for the Cultivation of Hemolytic Streptococcus

Abstract

In the preceding paper (Bernheimer and Pappenheimer, 1942) the factors necessary for massive growth of group A hemolytic streptococcus on a medium of essentially defined chemical composition were discussed. The medium has been adapted for heavy growth in large volumes. Although worked out specifically for the C203S strain, the medium has proved useful for the cultivation of other strains of group A streptococcus. The following solutions are prepared: Solution I: 10 liters of distilled water (Note 1), 7.5 grams MgSO4. 7H20, 150 mgm. uracil, 150 mgm. adenine sulfate and 110 mgm. phenol red are placed in a 20 liter Pyrex carboy and sterilized at 15 lbs. for 90 minutes in the autoclave. Solution II: To 3 liters of 10 per cent casein hydrolysate (Note 2) are added 2 grams cystine (dissolved separately in water with the aid of a little concentrated HCl), 45 grams KCl, 37.5 grams KH2PO4, 15 grams Na2HPO4.12H20, and 2 ml. of 0.4 per cent phenol red. The pH is adjusted with 20 per cent NaOH to 7.5-7.8 and the mixture boiled gently for 5 minutes and filtered. To the clear filtrate is added 0.015 mgm. biotin (Note 3), 15 mgm. nicotinic acid, 15 mgm. pyridoxine (vitamin B6) and 300 mgm. tryptophane (Note 4). This solution is then distributed into liter flasks, plugged and covered with paper caps and autoclaved at 15 lbs.