Final answer:
For short-term storage beyond 24 to 36 hours and to inhibit microbial growth, unused microbiology media should be stored in a refrigerator, while ultra-low freezers or liquid nitrogen tanks are used for long-term storage.
Step-by-step explanation:
Unused media intended for microbiology purposes should be stored in a way that preserves its utility while inhibiting unwanted microbial growth. The correct storage option depends on when you plan to use the media. For short-term storage, where you intend to use the media within a day, storing it at room temperature might be appropriate. However, if the media will not be used within the next 24 to 36 hours, the best option is to store it in the refrigerator. Refrigeration maintains temperatures between 0 °C and 7 °C, which significantly slows microbial metabolism and growth, helping to preserve the media. Media should not be kept in the incubator unless they are being actively cultured, as this could lead to dehydration of the media and the demise of any bacteria present.
On the other hand, for long-term storage or transport, freezing at ultra-low temperatures achieved by ultra-low freezers or liquid nitrogen tanks is ideal, especially for sensitive bacterial cultures and medical specimens. Freezers maintain temperatures well below -70 °C, greatly extending the viability of the stored material.