# 11b: MRS MEDIUM (pre-reduced) ## Main sol. 11b 10 g Casein peptone (tryptic digest) 10 g Meat extract 5 g Yeast extract 20 g Glucose 1 g Tween 80 1 mg Resazurin 2 g K2HPO4 5 g Na-acetate 2 g (NH4)3 citrate 0.2 g MgSO4 x 7 H2O 0.05 g MnSO4 x H2O 1000 ml Distilled water 0.5 g L-Cysteine HCl x H2O 1. Cysteine is added after the medium has been boiled and cooled under CO2. Adjust pH to 6.2 - 6.5, distribute under N2 and autoclave.