It seems like you are referring to "YM medium," which is a type of culture medium used for the growth and maintenance of microorganisms, especially bacteria. YM medium is typically used in microbiology and research laboratories.
Whether you can use YM medium stored in the fridge depends on several factors:
Expiration date: Check the expiration date of the YM medium. If it has passed the expiration date, it's best not to use it, as the components may have degraded, leading to unreliable results.
Contamination: If you observe any signs of contamination in the YM medium, such as mold growth or a foul smell, discard it immediately. Contaminated medium can affect the growth of the microorganisms you are trying to culture.
Temperature fluctuations: If the fridge where the YM medium is stored experiences frequent temperature fluctuations or if the medium has been repeatedly exposed to warmer temperatures, its quality and performance might be compromised.
Original condition: Ensure that the YM medium was appropriately stored in a sealed container or according to the manufacturer's recommendations.
Before using the YM medium, inspect it visually and use your judgment. If it appears normal and shows no signs of deterioration or contamination, it might still be usable. However, for critical experiments or sensitive work, it's generally better to use freshly prepared culture medium to ensure reliable and reproducible results. If you have any doubts about the quality or suitability of the medium, it's best to prepare a fresh batch to avoid potential issues in your experiments.