How To Handle Microbiological Media (Agar Plates)

Microbiological media can easily be contaminated with unwanted microorganisms if not handled properly. It is therefore important to learn how to hand microbiological media to ensure quality results.

1. Microbiological Media must be kept refrigerated or on ice until ready to use.
2. The plates must be allowed to warm up to room temperature before taking a sample (approx. 20 minutes).
3. Do not remove the lid from the plate at any time except during sampling.
4. The plates must be shipped back to MBL with OVERNIGHT PRIORITY. Use Refreeze and reuse icepack to keep them cool (this type of icepack is stable for 24 hours).
5. Adequate packing material must be sent to protect the plates. The weight of the icepack can crush the plates during shipping.
6. Plates must not come into direct contact with the ice, as the tests will be invalid if the media freezes.
7. If there is any delay in sending the agar plates to MBL, they should be refrigerated until ready for overnight delivery.
8. A Chain of Custody form must accompany the plates. Note on the CoC the date collected and the date sent to the laboratory.

Sampling Procedure

Depending on what you are sampling for, you either use mycological media such as malt extract agar (MEA) or bacteriological media such as TSA.

1. Allow agar plates to reach room temperature before use.
2. Attach one end of tubing to the intake of the quicktake 30 pump and the other end to the inlet of the biostage impactor.
3. Calibrate the flow rate of the vacuum pump (Done by MBL)
4. Place an uncovered Petri dish into sampler
5. Wipe all exposed surfaces of sampler with 70% Isopropyl alcohol and allow to air dry.
6. Place the agar plate on the base plate so that the Petri dish rests on the three raised metal pins.
7. Remove the cover of the Petri dish and place into a sterile sample bag to minimize contamination
8. Assemble the rest of the sampler and secure the inlet cone with the three attached clips or twice to close.
9. Set timer to appropriate time depending on environmental conditions (sampling time is between 2-5 minutes).
10. Turn on the pump and start the timer simultaneously.
11. When the time is up, turn off the pump and disassemble sampler and place cover back onto agar plate.
12. Secure lid onto Petri dish with masking tape or Parafilm (avoid using electrical, packing, transparent and duct tape).
13. Write the sample number on the bottom of the Petri dish.
14. Record all appropriate information on the Chain of Custody.

Sampling Tips

• Wear latex gloves during sampling
• Use 70% Isopropyl alcohol to sterilize sampler
• Place lid to Petri dish in a sterile bag during sampling
• Include an outside sample for a control and a blank.

Ship Samples to:
Mold & Bacteria Consulting Laboratories
1020 Brevik Place, Unit 1A,
Mississauga, Ontario L4W 4N7
(Attn: Laboratory Manager)

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