The growth medium for low temperature steam formaldehyde (LTSF) sterilization processes has been developed to incubate Geobacillus stearothermophilus spores
(# 7953) to easily monitor growth. After sterilization the spores, e.g. spore strips are aseptically transferred into the growth medium on a sterile bench and incubated at 55 - 60°C afterwards.

The medium contains a pH-indicator that shows bacteria growth quicker than conventional media. If not all spores were inactivated during the sterilization process, the germs replicate and produce acids. The resulting pH changes the colour of the liquid from purple to yellow-green.

The LTSF growth medium addtionally contains substances to decompose remaining absorbed formaldehyde so that the pre-treatment with Na₂SO₃ according to EN ISO 11138-5 is not required anymore and the results can be obtained much faster.