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Microbiology—Media, continued
3M® Petrifilm™ Plates
Each Petrifilm™ “plate” consists of two plastic film sheets with the sterile culture
media in between. The sheets are separated briefly for inoculation with the
material of your choice and then resealed and incubated. Growth occurs on the
super thin film of media just like it does on the surface of an agar plate. You can
stack a class set in the same space as one Petri dish. Results are visible through
the clear film, and colonies are readily viewed. Transfers are possible but not
necessary. Disposal becomes easier. Once inoculated, the plates need never be
opened again. Petrifilm can be kept for 18 months if refrigerated. Fifty plates take
up as much space as one Petri dish. Ready to use with various media.
Petrifilm Aerobic Count Plates: Use in place of regular nutrient agar plates.
Especially useful if conducting air sampling experiments or other air pollution studies.
Petrifilm Yeast and Mold Count Plates: Count yeast and mold colonies on
these plates. An indicator dye stains yeast and mold colonies to provide contrast
and facilitate counting.
Petrifilm E. coli/Coliform Count Plates: An indicator dye makes counting
coliforms easy. The coliforms produce red colonies. These plates contain an additional
indicator dye that forms blue around E. coli colonies. Counting red and blue
colonies yields the total coliform count.
Yeast and Mold Spreader: Specially designed for Petrifilm Yeast and Mold
Count Plates (FB1172). Simply press down on top of the spreader to create a circular
pattern. Spreaders are reusable.
Petrifilm Spreader: Use with Aerobic Count Plates (FB1171) and Coliform Plates
(FB1173). Spreaders are reusable.
See free video at flinnsci.com.
Catalog No. Description Price/Pkg.
FB1171 Petrifilm™ Aerobic Count Plate $79.80/50
FB1172 Petrifilm™ Yeast and Mold Count Plate 92.60/50
FB1173 Petrifilm™ E. coli/Coliform Count Plates 81.70/25
FB1114 Yeast and Mold Spreader 1.31
FB1134 Petrifilm™ Spreader 1.04
MICROBIOLOGY—CULTURE SUPPLIES continued on next page.
The steps in making agar Petri dishes should be carefully followed to maintain sterile
conditions from the onset of an experiment. (This procedure assumes that the Petri
dishes and the media have been sterilized.)
1. If the agar has solidified, stand the tubes (or other media container) in a warm water
bath until the media melts to liquid form with no lumps remaining.
2. Wet down the working area with a sponge and disinfectant. Avoid air drafts while
plating. The less people walk around the work area the better.
3. Line up the Petri dishes near the edge of the table in a single file for quick and easy
access.
4. Use a Bunsen burner and position the burner for minimal distance to the Petri
dishes.
5. Use one of the melted agar tubes. Remove the cap or plug and flame the mouth of
the test tube by passing it through the flame of the Bunsen burner to sterilize the
rim of the test tube.
BIOLOGY MICROBIOLOGY
6. Only open the Petri dish to pour the liquid media into the dish. Lift the cover straight
up and keep it straight above the bottom half of the dish. Do this while trying not to
create any wind currents.
7. Pour the liquid media into the Petri dish and cover the bottom half of the plate.
8. Replace the cover on the dish immediately and then gently swirl (if necessary) the
dish so that the medium is evenly distributed in a thin film.
9. Let the dish sit undisturbed until the media solidifies.
10. When all the poured dishes have solidified, invert the dishes to prevent condensation
from falling back onto the agar.
11. Refrigeration can help prevent contamination. Dishes can be stored in a refrigerator
for a week or so before use.
Make Agar Petri Dishes
No More Valuable Preparation Time Spent
Autoclaving Petri Dishes—
Petrifilm™ Plates are Ready to Use!
3M® Petrifilm™
FB1171, etc.
Microbiology—Culture Supplies
Petri Dishes, Borosilicate
Tops and bottoms are marked with different colored enamels.
Catalog No. Description Price/Each
GP3019 Petri Dish, Borosilicate, 100 x 15 mm $47.25/6
GP3020 88.35/12
Petri Dish, Borosilicate
GP3019, etc.
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