CRITERION™ m-FC AGAR BASE

Cat. no. C6270 CRITERION™ m-FC Agar Base 104gm
Cat. no. C6271 CRITERION™ m-FC Agar Base 500gm
Cat. no. C6272 CRITERION™ m-FC Agar Base 2kg
Cat. no. C6273 CRITERION™ m-FC Agar Base 10kg
Cat. no. C6274 CRITERION™ m-FC Agar Base 50kg

INTENDED USE

Hardy Diagnostics CRITERION™ m-FC Agar Base is recommended for the cultivation and enumeration of fecal coliforms in water samples using the membrane filtration technique at elevated temperatures. Rosolic acid may be added to the media as a selective agent to further inhibit undesirable microorganisms during testing.

SUMMARY

Geldreich et al. formulated a medium to enumerate fecal coliforms (m-FC) using the membrane filter (MF) technique without prior enrichment.(1) Fecal coliforms, which are found in the gastrointestinal tracts and feces of warm-blooded animals, are differentiated from coliforms from environmental sources by their ability to grow at elevated temperatures: 44.5 +/- 0.2ºC.(2)

The m-FC method for detection of fecal coliforms can be used for monitoring all types of water. Because many coliforms occur naturally in environmental sources as well as through fecal contamination, Escherichia coli is recommended as the required indicator for freshwater testing and E. coli or enterococci as the required indicators for marine water testing since these microorganisms are known fecal contaminants.(5)

Hardy Diagnostics CRITERION™ m-FC Agar Base contains peptones as a source of carbon, nitrogen, vitamins and minerals. Yeast extract supplies B-complex vitamins that help stimulate bacterial growth. Lactose is a carbohydrate that can be fermented by fecal coliforms at elevated temperatures. Bile salts no. 3 inhibits the growth of undesirable gram-positive microbial flora and, when added, rosolic acid will further inhibit the growth of undesirable microorganisms. m-FC Agar Base contains agar as the solidifying agent. The differential indicator is aniline blue, which demonstrates the ability of fecal coliforms to ferment lactose to acid causing color change in the medium.

FORMULA*

Gram weight per liter: 52.0gm/L
Lactose 12.5gm
Tryptose 10.0gm
Sodium Chloride 5.0gm
Proteose Peptone No. 3 5.0gm
Yeast Extract 3.0gm
Bile Salts No. 3 1.5gm
Aniline Blue 0.1gm
1% Rosolic Acid** 10.0ml
Agar 15.0gm

** 1% Rosolic Acid (when added)
Composition per 100ml, 0.2N Sodium Hydroxide
Rosolic Acid 1.0gm

Final pH 7.4 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if it is not free-flowing or if the color has changed from its original beige with a slight blue tint.

Store the prepared culture media at 2-30ºC.

PRECAUTIONS

METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA

1. Dissolve 52.0gm of the dehydrated culture media in 1 liter of distilled or deionized water. Stir to mix thoroughly.

2. Heat to boiling to dissolve completely. DO NOT OVERHEAT.

3. If desired, add 10ml of 1% rosolic acid solution prepared in 0.2N NaOH.

4. Continue heating for one minute. DO NOT AUTOCLAVE.

PROCEDURE

Sample Collection: Consult listed references for information on sample collection. (2,6-9)

Method of Use:

1. Prepare agar medium from dehydrated base according to the label directions outlined above.

2. Pour molten (cooled to 45-50ºC.) agar into tight-fitting petri plates and allow it to harden.

3. Filter duplicate water specimens through separate membrane filters.

4. Roll membrane filter used to collect the water sample onto the agar surface. Avoid the formation of air bubbles between the filter and agar surface.

5. Place plates into separate waterproof plastic bags and seal bags to prevent leakage.

6. Incubate plates, by immersion, in two separate waterbaths: one set at 35 +/- 2ºC. and the other at 44.5 +/- 0.2ºC.

7. Anchor plates below water surface to maintain critical temperature requirements and incubate for 24 +/- 2 hours. Place all inoculated plates in waterbath within 30 minutes after filtration for best results. As an alternative, an appropriate and accurate solid heat sink or equivalent incubator may be used.

INTERPRETATION OF RESULTS

Colonies produced by fecal coliforms will appear as varying shades of blue-colored colonies on the membrane filter. Coliforms from other sources should be inhibited; however, if present they may appear as gray to cream-colored colonies.

Calculate fecal coliform densities as directed by listed references.(2,4-6)

LIMITATIONS

Even with the selective action of the elevated incubation temperature and, when added, rosolic acid, a few non-fecal coliforms may be observed. To eliminate the potential for Klebsiella contamination, it may be helpful to elevate the incubation temperature to 45 +/- 0.2ºC.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as autoclaves, incinerators, sodium hydroxide, rosolic acid, membrane filters, petri plates, plastic bags, incubators and waterbaths, etc., are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Escherichia coli
ATCC ® 25922
MF 24hr 44.5°C Aerobic Growth; blue colonies/media
Enterobacter aerogenes
ATCC ® 13048
MF 24hr 44.5°C Aerobic No growth; may be a film

User Quality Control

Physical Appearance

CRITERION™ m-FC Agar Base should appear homogeneous, free-flowing, and beige with a slight blue tint. The prepared media, when supplemented with rosolic acid, should appear clear, slightly opalescent and cranberry in color.

REFERENCES

1. Geldreich E.E., H.F. Clark, C.B. Huff, and L.C. Best. 1965. Fecal Coliform Organism Medium for the Membrane Filter Technique. J. Am. Water Works Assoc.; 57:208-214.

2. American Public Health Association. 2005. Standard Methods for the Examination of Water and Wastewater, 21st ed. APHA, Washington, D.C.

3. Horwitz, W. 2000. Official methods of analysis of AOAC International, 17th ed. AOAC International. Gaithersburg, MD.

4. U.S. Environmental Protection Agency. 1992. Manual for the Certification of Laboratories Analyzing Drinking Water. EPA-814B-92-002. Office of Ground Water and Technical Support Division, USEPA, Cincinnati, OH.

5. Bordner, R.H., J.A. Winter and P.V. Scarpino. 1978. Microbiological Methods for Monitoring the Environment: Water and Wastes. Publication EPA-600/8-78-017. Environmental Monitoring and Support Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH.

6. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

7. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

8. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

9. Association of Official Analytical Chemists. Official Methods of Analysissm, AOAC, Washington, D.C.


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062916gr