Nutrient-TTC Agar is a general purpose (relatively non-selective) medium, which will support the growth of a wide variety of organisms. Suitable for cultivation of both aerobes and anaerobes. Aerobic coliform bacteria can be detected by their ability to reduce the TTC dye to a red-colored formozan dye. Bacterial colonies appear as red dots on an otherwise yellow medium.
R2A Agar, in combination with a lower incubation temperature and longer incubation time, stimulates the growth of stressed and chlorine-tolerant bacteria. R2A Agar is recommended in Standard Methods for the Examination of Water and Wastewater for pour plate, spread plate and membrane filter methods for heterotrophic counts.