Scribd
Upload
49 views1 page

Bacillus Cereus Medium: Phenol Red Egg Yolk Polymyxin Agar (P.R.E.P.) Mannitol Egg Yolk Polymyxin Agar

The document describes a Bacillus Cereus Medium used for enumerating Bacillus cereus in foods. It was introduced in 1967 and shown to be most effective by differentiating B. cereus from other Bacillus based on mannitol fermentation and lecithinase production. The medium composition, preparation instructions, expected growth characteristics, and references are provided.

Uploaded by

Prabin Koirala
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
49 views1 page

Bacillus Cereus Medium: Phenol Red Egg Yolk Polymyxin Agar (P.R.E.P.) Mannitol Egg Yolk Polymyxin Agar

The document describes a Bacillus Cereus Medium used for enumerating Bacillus cereus in foods. It was introduced in 1967 and shown to be most effective by differentiating B. cereus from other Bacillus based on mannitol fermentation and lecithinase production. The medium composition, preparation instructions, expected growth characteristics, and references are provided.

Uploaded by

Prabin Koirala
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
You are on page 1/ 1

Bacillus Cereus Medium

Phenol Red Egg Yolk Polymyxin Agar (P.R.E.P.)


Mannitol Egg Yolk Polymyxin Agar
LAB 73

Description
Introduced by Mossel and his co-workers in 1967 for the enumeration of Bacillus cereus in foods, this formula was shown to be the most
effective for this purpose by Inal in 1972. Two reactions on this medium differentiate B. cereus from other members of the Bacillus group,
these are mannitol fermentation and lecithinase production. Mannitol fermentation on this medium produces a yellow colour, B. cereus is
mannitol negative and produces red colonies. The lecithinase production of B. cereus is indicated by a white precipitate around the
colonies. Polymyxin is added to suppress coliforms but some Proteus spp and Gram positive cocci may grow through.
Typical Formula g/litre
Beef Extract 1.0
Balanced Peptone No. 1 10.0
D-Mannitol 10.0
Sodium chloride 10.0
Phenol red 0.025
Agar No. 1 15.0

Method for reconstitution


Weigh 46 grams of powder, disperse in 900ml of deionised water. Allow to soak for 10 minutes, swirl to mix then sterilise by autoclaving
at 121°C for 15 minutes. Cool to 47°C and aseptically add 100ml of X073 egg yolk emulsion and 2 vials of X074 Polymyxin.
Appearance: Pink, opaque gel.
pH: 7.2 ± 0.2
Minimum Q.C. organisms: B. cereus WDCM 00013
E. coli (inhibition) WDCM 00063

Storage of Prepared Medium: – up to 7 days at 2-8°C in the dark.


Inoculation: Surface, spreading or streaking for single colonies.
Incubation: 30°C aerobically for 24-48 hours.
Growth Characteristics
organism colony size (mm) shape & surface colour
B. cereus 3.0-4.0 F.CR.D. Pink, white halo
B. subtilis 2.0-3.0 F.CR.D. Yellow
B. licheniformis 2.0 F.Rz.D. Yellow
E. coli no growth
S. aureus 1.0 CV.E.G. Yellow (white halo)

References
Inal, T.: Vergleictiende Untersuchungen über die Selektivmedien zum qualitativen und quantitativen Nachweis von Vacillus cereus in
Lebensmitteln. Mitteilung I. : Fleischwritsch, 51: 1629-1632 (1971). IV. Mitteilung: Fleischwritsch, 52: 1160-1162 (1972).
Mossel, D.A.A., Koopman, M.J. and Jongerius, E. (1967). Enumeration of Bacillus cereus in foods. Appl. Microbiol. 15: 650-653.
Thatcher, F.S., Clarke, D.S. (1978) Micro-organisms in foods. Volume 1 second edition. University of Toronto.
BS5763 Part 1L:1994. ISO7932:(1993) 3/100

LAB073_02

You might also like