Carolina 3M Petrifilm Aerobic Count Plates User Manual

82-4000

3M™ Petrifilm™

Aerobic Count Plates

Instruction Manual

CAROLINA

®

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Description

The 3M™ Petrifilm™ Aerobic Count (AC) Plate is a ready-made culture
medium system that contains nutrients, a cold-water-soluble gelling agent,
and an indicator dye that makes colonies easier to see. Petrifilm plates are
manufactured with a grid background to facilitate counting colonies.
Petrifilm AC plates can be used in place of standard nutrient media such as
Luria broth agar plates, nutrient agar plates, or trypticase soya agar plates in
many applications:

• Petrifilm plates can be hydrated with a bacterial culture, or a dilution of a
culture, for counting the viable organisms present. See Method A.

• Petrifilm plates can be hydrated first with water or buffer, then inoculated
by swabbing, streaking, or touching to surfaces. See Method B.

• Antibiotics can be added to the hydration fluid to select for resistant
organisms in Method A or B.

• Cells can be removed from colonies growing on Petrifilm plates and used
to inoculate additional cultures or for staining.

• Experimental results on Petrifilm plates can be saved for future reference
by scanning the plates on a standard computer-linked scanner. Do not
open the plates for scanning.

Petrifilm plates were developed for use in the food and beverage industry.
They have been certified for official analyses in many countries. For more
information about these applications, see the 3M page on the World Wide
Web at www.3m.com.

Storage

Refrigerate unopened packages at ≤ 8˚C (≤46˚F). Use before expiration date on
package.

To seal an opened package, fold the end over and tape it shut (fig. 1). Keep
resealed packages at room temperature and less than 50% relative humidity.
Do not refrigerate opened packages. Use plates from the opened package
within one month after opening.

©1999 Carolina Biological Supply Company Printed in USA

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Figure 1

Directions for Use

Use sterile technique when handling Petrifilm plates. Disinfect the work
area by wiping throughly with alcohol or other disinfectant before and after
use. Used Petrifilm plates may contain viable organisms. Do not open the
plates unnecessarily.

Method A. Inoculation with liquid sample

1. If a Petrifilm plate pack has been stored in the refrigerator, let the

package come to room temperature before opening it. This step
prevents condensation from forming inside the package.

2. Place the Petrifilm plate on a level surface, with the grid side down. Lift

the top film (fig. 2).

Figure 2