Rose-Bengal Chloramphenicol Agar is a selective medium for the enumeration of yeasts and moulds from a wide variety of foodstuffs. The medium has a neutral pH and chloramphenicol is used as a selective agent to suppress the growth of bacteria. Several investigators have noted advantages in the use of media at neutral pH containing antibiotics1,2. Rose-Bengal is taken up by mould and yeast colonies thereby assisting enumeration of small colonies3. Rose-Bengal also controls the size and height of mould colonies, such as Neurospora and Rhizopus spp. Over-growth of slow growing strains by more luxuriant species is thus prevented and plate counting is assisted. The slide is double sided and the other side contains Nutrient Agar with TTC ( Triphenyltetrazolium Chloride). This is a general purpose agar medium, containing two peptones, which will support the growth of a wide variety of organisms. It is suitable for the cultivation both of aerobes and anaerobes, the latter being grown either in deep cultures or by incubation under anaerobic conditions. A small quantity of the dye 2,3,5- triphenyltetrazolium (TTC) is added. Aerobic bacteria species grow on this medium and they can be detected by their ability to reduce TTC to a red colored formozan dye. Bacterial colonies appear as red dots on an otherwise clear colorless medium. |