# 830d: R2A MEDIUM (MICROAEROBIC)


## Main sol. 830d

0.5	g	Yeast extract	
0.5	g	Proteose peptone (BD DIFCO no. 3)	
0.5	g	Casamino acids	
0.5	g	Glucose	
0.5	g	Starch, soluble	
0.3	g	Na-pyruvate	
0.3	g	K2HPO4	
0.05	g	MgSO4 x 7 H2O	
1000	ml	Distilled water	

1. Dissolve ingredients, then sparge solution with 80% N2 and 20% CO2 gas mixture for at least 30 - 45 min to remove dissolved oxygen and to saturate the solution with CO2. Dispense solution in vials suitable for anaerobic cultures (e.g. Balch-type tubes or serum vials) to 75% volume under air atmosphere. Close vials with butyl rubber septa to prevent free exchange of oxygen with the external atmosphere and autoclave. Adjust pH of the autoclaved medium to 5.0 - 5.5 using a sterile stock solution of sodium carbonate (5% w/v), prepared under 80% N2 and 20% CO2 gas mixture.