The storage conditions of the universal transport medium are usually influenced by factors such as its composition, stability, and intended use. Generally, the following are the common storage conditions:

• Temperature Conditions
  • Room Temperature Storage: Some universal transport media can be stored and transported at room temperature (usually referring to 15°C – 30°C). Such transport media typically contain special stabilizers and protective agents, which can ensure the stability of the sample and the transport medium for a certain period of time. However, the storage time at room temperature is generally short and may only be suitable for transportation and use within a few hours to a few days. It is often used for samples that are not particularly sensitive to temperature or for short-distance and rapid transportation.
  • Refrigerated Storage: Most universal transport media need to be stored under refrigerated conditions, generally within a temperature range of 2°C – 8°C. Within this temperature range, the components in the transport medium can maintain good stability, and the reproduction and metabolism of microorganisms can be inhibited to a certain extent. This is beneficial for prolonging the shelf life of the transport medium itself and maintaining the activity of the biological components in the sample. It can be stored for several days to several weeks, and the specific duration depends on the formulation and characteristics of the transport medium.
  • Frozen Storage: For some special universal transport media or situations requiring long-term storage, it may be necessary to store them under frozen conditions, such as at -20°C or a lower temperature. Frozen storage can greatly reduce the activity of biological molecules and the rate of chemical reactions, effectively preventing the degradation and deterioration of biological components in the sample. It is suitable for samples that need to be stored or transported for a long time. However, the frozen transport medium needs appropriate thawing treatment before use, and attention should be paid to avoiding temperature fluctuations and damage to the sample caused by ice crystals during the thawing process.
• Humidity Conditions: The universal transport medium generally should be stored in a relatively dry environment to prevent the components in the transport medium from deteriorating, degrading, or being contaminated by microorganisms due to moisture. Usually, a relative humidity of 30% – 60% is more appropriate, but different transport media may have slightly different requirements for humidity.
• Lighting Conditions: Most universal transport media should be kept away from direct sunlight and strong light exposure because lighting may trigger photochemical reactions in some components of the transport medium, leading to changes in composition, a decline in performance, and affecting its protective and transport effects on the sample. Therefore, it is generally necessary to store them in a dark environment, such as using brown bottles for packaging or placing them in a light-shielded cabinet or box.
• Other Conditions
  • Sealed Storage: The universal transport medium should be kept in a sealed state to prevent the loss of moisture, the entry of external contaminants, and the volatilization of volatile components in the transport medium, which may affect its performance.
  • Avoid Vibration: Violent vibration may damage the structural composition of the transport medium or cause physical damage to the sample. Especially for transport media containing biological samples such as cells or viruses, vibration should be minimized during storage and transportation.

Different brands and types of universal transport media may have different specific storage conditions. In actual use, the storage should be carried out strictly according to the requirements specified in the product manual.