It seems like you are referring to a specific medium called "YM medium." However, without additional context, it's challenging to determine precisely what "YM medium" you are referring to. Different industries and scientific fields may use abbreviations that have specific meanings within their context.
If "YM medium" refers to a type of microbiological or cell culture medium, it's essential to follow the manufacturer's recommendations and guidelines for storage and usage. Generally, many culture media can be stored in the refrigerator to extend their shelf life, but the specific requirements can vary depending on the composition of the medium and the organisms or cells it supports.
To ensure that you use the "YM medium" correctly and safely, I recommend checking the product label or referring to the manufacturer's instructions. The label or product information should provide details on the recommended storage conditions, expiration date, and any specific instructions for using the medium after refrigeration. If you have any doubts or questions about the medium's use or storage, it's best to consult with a knowledgeable laboratory professional or the manufacturer directly.