In contrast,chloramphenicol(100-300mg/l)is heat stable and can be added to the medium prior to sterilization. Antifungal antibiotics,which suppress filamentous fungi,should be used with caution to avoid growth inhibiting effects on yeasts.Such antifungals include cycloheximide(100-500mg/l),cyclosporin A (4-10mg/l)and pimaricin(5-100mg/l).