OxyPRAS BHI Broth is a pre-reduced anaerobically sterilized nutritionally enriched medium that is reduced with cysteine and used for growing anaerobes. Anaerobic sterilization of a reduced medium prevents formation of undesirable oxidation products that interfere with growth of anaerobes. support growth of fastidious anaerobes. OxyPRAS BHI Broth is cell-free and will not interfere with gram stain interpretation of cultures grown in it. It is the preferred broth medium for Oxyrase for Broth and AnaSelect Oxyrase for Broth.