Fluid Thioglycollate Medium (FTM)

A sterility test medium that supports anaerobic and aerobic bacteria, incubated at 30–35 °C for at least 14 days. Thioglycollate and a small amount of agar lower the oxygen level, so anaerobes can grow in the deeper part while aerobes grow near the surface. Resazurin acts as an oxygen indicator, turning pink when oxidised. If more than one third of the medium is pink before use, it can be restored once by heating.