3M Petrifilm Aerobic Count Plate Interpretation Guide

Petrifilm BrandInterpretationGuideThe 3M Petrifilm Aerobic Count Plate is aready-made culture medium system thatcontains modified Standard Methods nutrients,a cold-water-soluble gelling agent and an indicatorthat facilitates colony enumeration. 3M Petrifilm Aerobic Count Plates are used for the enumerationof aerobic bacteria.ACAerobic Count Plate

Figure 1Figure 2Aerobic bacteria count 0Aerobic bacteria count 163M Petrifilm Aerobic Count Plate without colonies.3M Petrifilm Aerobic Count Plate with a few bacterial colonies. Figure 3Figure 4Aerobic bacteria count 143Estimated aerobic bacteria count 560The preferred counting range on a 3M Petrifilm AerobicCount Plate is less than or equal to 300 colonies.When colonies number more than 300, estimate the count.Determine the average number of colonies in one square(1 cm2) and multiply it by 20 to obtain the total count perplate. The inoculated area on a 3M Petrifilm AerobicCount Plate is approximately 20 cm2.For a more accurate count, further dilution of the samplemay be necessary.Aerobic Count Plate2

Too Numerous to Count (TNTC)Figure 5Figure 6Aerobic bacteria count TNTCAerobic bacteria count TNTC3M Petrifilm Aerobic Count Plate with colonies that are TNTC.With very high counts, the entire growth area may turnpink. You may observe individual colonies only at the edgeof the growth area. Record this as a TNTC result. For a more accurate count, further dilution of the samplemay be necessary.Figure 7For a more accurate count, further dilution of the samplemay be necessary.Figure 8Aerobic bacteria count TNTCAerobic bacteria count TNTCOccasionally, distribution of colonies appears uneven. This isalso an indication of a TNTC result.The colonies on the 3M Petrifilm Aerobic Count Plate mayappear countable at first glance. However, when you lookclosely at the edge of the growth area, you can see a highconcentration of colonies. Record this as a TNTC result.For a more accurate count, further dilution of the samplemay be necessary.For a more accurate count, further dilution of the samplemay be necessary.3

Gel Liquefication and Food Particles12Figure 9Figure 10Estimated aerobic bacteria count 160Aerobic bacteria count 83A few species of bacteria liquify the gel in the 3M Petrifilm Aerobic Count Plate. When this occurs, determine the averagecount in a few unaffected squares and then multiply it by 20 toobtain the estimated count. Do not count red spots within theliquified area.Because colonies on 3M Petrifilm Aerobic Count Plateare red, you can distinguish them from opaque, irregularlyshaped food particles (see circles 1 and 2).For a more accurate count, further dilution of the samplemay be necessary.4

Reminders for UseStorage Petrifilm Aerobic 8 C1Store unopened pouches of platesrefrigerated or frozen at temperatureslower than or equal to 8 C (46 F).Use before expiration date on package.Just prior to use, allow unopenedpouches to come to room temperature.2Seal by folding the end of the pouch overand applying adhesive tape. To preventexposure to moisture, do not refrigerateopened pouches. Store resealedpouches in a cool, dry place for nolonger than four weeks. Avoid exposureof plates to temperatures 25 C( 77 F)PrintedColors – Front:and/or relative humidity 50%.Requester:Creator:File Name:Structure #:Date:InoculationSusan BarkerdeZinnia 21698Standard Pouch 21698FS.aiIllustration05/08/17Scale:1 InchThis artwork has been created as requested by 3M. 3M is responsible for the artworkAS APPROVED and assumes full responsibility for its correctness.3Place 3M Petrifilm Aerobic Count Plateon level surface. Lift top film.4With 3M Electronic Pipettor orequivalent held perpendicular to plate,place 1 mL of sample or diluted sampleonto centre of bottom film.6With ridge side down, place3M Petrifilm Spreader on top filmover inoculum.7Gently apply pressure on 3M Petrifilm Spreader to distribute inoculum overcircular area before gel is formed.Do not twist or slide the spreader. Lift3M Petrifilm Spreader. Wait a minimumof 1 minute for gel to solidify.Aerobic Count Plate5Drop the top film down onto the sample.5

IncubationInterpretationUse AppropiateSterile DiluentsThese include Butterfield’s phosphatebuffered dilution water, 0.1% peptonewater, peptone salt diluent, bufferedpeptone water, dipotassium hydrogenphosphate solution, saline solution(0.85-0.90%), bisulfite-free letheenbroth or distilled water.Incubate plates with clear side upin stacks of up to 20. It may benecessary to humidify incubator toPrinted Colors – Front:minimize moisture loss. Please referRequester:toSusantheBarkerproduct instructions forCreator:deZinnia 21849methods.File Name:third-party-validatedPetrifilm 21849-07 FS.aiScale:8Structure #: IllustrationDate:04/17/1791 InchThis artwork has been created as requested by 3M. 3M is responsible for the artworkAS APPROVED and assumes full responsibility for its correctness.3M Petrifilm Aerobic Count Plates canbe counted with the 3M Petrifilm PlateReader, on a standard colony counter orother illuminated magnifier.For optimal growth and recovery of themicroorganisms, adjust the pH of thesample suspension to 6.6–7.2.Do not use diluents containingcitrate, bisulfite or thiosulfate with3M Petrifilm Aerobic Count Plates;they can inhibit growth.If citrate buffer is indicated in the standardprocedure, substitute with one of thebuffers listed above, warmed to 40–45 C.3M Food Safety offers a full line ofproducts to accomplish a variety ofyour microbial testing needs. Formore product information, visit usat 3M.ca/Foodsafety/Petrifilmor call 1-800-328-6553.User’s Responsibilities: 3M Petrifilm Plate performance has not been evaluated with allcombinations of microbial flora, incubation conditions and food matrices. It is the user’s responsibilityto determine that any test methods and results meet the user’s requirements. Should re-printing of thisInterpretation Guide be necessary, user’s print settings may impact picture and colour quality.3M Food Safety3M CanadaP.O. Box 5757London, Ontario N6A 4T11-800-364-3577Aerobic Count PlateFor detailed CAUTIONS, DISCLAIMER OF WARRANTIES/LIMITED REMEDYand LIMITATION OF 3M LIABILITY, STORAGE AND DISPOSAL informationand INSTRUCTIONS FOR USE, see product’s package insert.3M and Petrifilm are trademarks of 3M. Used under license in Canada. 2018, 3M. All rights reserved. 1804-11820 E BA-18-261326

The 3M Petrifilm Aerobic Count Plate is a ready-made culture medium system that contains modified Standard Methods nutrients, a cold-water-soluble gelling agent and an indicator that facilitates colony enumeration. 3M Petrifilm Aerobic Count Plates are used for the enumeration of aerobic bacteria. AC Aerobic Count Plate .File Size: 2MB