Practical Tips
General Tips
Do’s:
- Purchase the order volume based on your needs. If you use certain media on a daily basis and in large quantities, buy a batch with a long expiration date that covers your annual needs so that you don’t have to worry about controlling the quality of new batches with each purchase.
- Purchase low-consumption media in small packaging.
- Purchase media susceptible to clumping, such as XLD and SS Agar, in small packaging.
- Provide proper storage conditions in a cool and dry place.
Don’ts:
- Order a small quantity of high-consumption media.
- Order a large quantity of low-consumption media with large packaging.
- Order a large quantity without having suitable storage conditions. (If you need a large quantity of media but do not have suitable storage conditions, coordinate with ibersco).
Dos:
- Check the expiration date of the product.
- Check if the container lid is sealed and has a nylon cover.
- Physically examine the powder and ensure its natural form.
Don’ts:
- Accept expired culture media, unsealed container lids, container without a nylon cover, clumpy media, or powder with color changes. (Report immediately to the company upon receiving.)
Do’s:
- Store the culture container at room temperature (25 degrees Celsius), and in special cases such as MRS culture media, store in the refrigerator.
- Completely seal the lid of the container after each use.
- Store in a dry and low-humidity place.
Don’ts:
- Place the culture container near a heater or radiator.
- Leave the lid of the tube open, even for a short time.
- Place near a sink or any type of liquid solution.
Dos:
- Control and adjust the pH if necessary.
- Use reliable distilled water.
- Regularly monitor and control the hardness and pH of the water used.
- Use a calibrated autoclave with appropriate time and temperature settings for sterilization.
- Fill up to one third of the bottle with the medium for sterilization.
- Fully comply with the preparation guidelines on the container label.
Don’ts:
- Use medium without pH control.
- Use tap water or any unreliable water source.
- Use a non-standard autoclave with excessive start and end time or high or low temperature.
- Sterilize a volume of medium greater than one third of the bottle volume.
- Autoclave media that cannot be autoclaved.
- Please use calibrated and standardized autoclaves. High temperatures for long periods of time in some autoclaves can lead to changes in the structure of the culture medium, changes in pH, burning of sugars, and changes in the color of the medium. Note: The sterilization process is often done at a temperature of 121 degrees for 15 minutes and the entire process from the start to the end of autoclaving should not exceed 45 to 50 minutes.
Practical Tips
Possible reasons:
Excessive heating and burning of the components of the medium, including sugars.
Troubleshooting:
Adjusting the temperature and heating time, for example, media with high glucose content such as MRS should never be subjected to long heating times in non-standard autoclaves and will caramelize.
Possible reasons:
- Incomplete dissolution of agar in the medium
- Improper pH adjustment of the medium
- Addition of solutions to the medium
- Inaccurate weighing
Troubleshooting:
- Make sure agar is completely dissolved.
- After autoclaving, shake the medium slightly.
- In non-autoclaved media, completely dissolve agar by indirect heat.
- The presence of small particles sticking to the container indicates incomplete dissolution of agar.
- pH being too high or low can have a serious effect on the consistency of agar medium, so make sure the pH is adjusted properly.
- Consider the volume of added solutions when preparing media so that the final volume is obtained after adding this volume.
- Ensure that your powder is weighed correctly and accurately. The scale must be calibrated and the weighed amounts must be accurate.
Possible reasons:
- Presence of moisture and heat in the storage area of the medium
- Complete or partial opening of the container lid
- Very moisture-absorbing media such as XLD Agar
Troubleshooting:
- Store the medium in a cool and dry place
- Make sure to close the container lid tightly immediately after weighing
- In addition to the above, it is better to prepare the medium in minimal volumes and not store for a long time.
It is essential to immediately check the physical condition of the medium after receiving it! In case of any issues, contact the company immediately.
Possible reasons:
- Incorrect pH of the medium
- Changes in the composition of the medium
- Use of inappropriate supplements and antibiotics
- Inactivity or death of the target organisms
- Bacterial inoculation at high temperatures
Troubleshooting:
- Use standard strains to control the performance of culture media.
- Check the pH of the medium after autoclaving.
- Avoid excessive heat.
- Ensure proper function of supplements and antibiotics used.
- Obtain supplements and antibiotics from reputable companies.
- Use appropriate doses of growth inhibitors and additives, not excessive amounts.
- Control the performance of growth essential supplements.
- Ensure viability of target organisms, for example, use fresh cultures instead of repeatedly freezing and thawing cultures, which can lead to their death. Use a sterile and cool loop for culture.
- Inoculate an appropriate volume of bacteria.
- Ensure that environmental samples such as soil, blood, etc., are not contaminated with growth-inhibiting substances such as antibiotics and heavy metals.
- It is often better to add strains to the medium at room temperature, 25 degrees Celsius.
Possible reasons:
- Incomplete dissolution of components, such as agar
- Use of inappropriate water for preparing the medium
- Excessive heat exposure of the medium
- Use of contaminated containers and preparation equipment
- Improper weighing and use of amounts greater than indicated on the product label
Troubleshooting:
- Fully dissolve the medium components in water before autoclaving.
- Use distilled water that is safe in terms of pH and salts (inappropriate pH and salt content of water can cause media to become cloudy).
- Ensure autoclave calibration.
- Avoid leaving the medium in the autoclave after the process is complete.
- Ensure complete cleanliness of glassware and equipment used for medium preparation.
- Ensure the calibration of the scale and the accuracy of the weighing conditions and amounts of powder used.
