Complete modifi ed TYI-S-33 can be stored for
several days at 4°C. The presence of a white precipitate/crystals (likely cystine) at the bottom of the bottle
is one indication that the medium is no longer useable
and should be discarded.
Culture medium can be aliquoted into 50 ml culture
tubes, parafi lmed, and stored at –20°C for future use.
Check sterility of media by incubating one or more
tubes containing media only at 37°C. Also, streak out
samples of media periodically on LB agar plates.