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MacConkey Broth

Name: MacConkey Broth
SKU: MCB-ML
Availability: InStock

MacConkey Broth

$35.00 – $160.00

9 mL, 90 mL, Custom
Number of sizes: 2
Type: Liquid

Prepared Media – Tubes

No sub-products available for this product.

SKU: MCB-ML Category: Ready To Use – Tubes

Description

Intended Use and Principle of Procedure

MacConkey Broth is used for cultivating gram-negative, lactose-fermenting bacilli in water and foods as a presumptive test for coliform organisms.

Peptone provides amino acids and other growth factors. Lactose is a carbon energy source for gram-negative lactosefermenting bacilli. Oxgall inhibits the growth of grampositive organisms. Bromcresol purple is the indicator.

Summary and Explanation

MacConkey Broth is a modification of the original bile salt broth recommended by MacConkey that contained 0.5% sodium taurocholate and litmus as an indicator. In later publications, MacConkey suggested variations of this formulation using neutral red indicator instead of litmus. Childs and Allen demonstrated the inhibitory effect of neutral red and substituted the less inhibitory bromcresol purple. Oxgall in the medium replaces the original sodium taurocholate to inhibit growth of gram-positive organisms.

Formulae

Oxgall	5.0g
Peptone	20.0g
Lactose	10.0g
Bromcresol Purple	0.01g

Procedure

Inoculate tubes with the test specimen. Incubate tubes for 18-24 hours at 35 ± 2°C in an aerobic atmosphere.

Directions for Preparation from Dehydrated Product

1. Dissolve 35 g of the powder in 1 L of purified water. For testing 10 mL samples, prepare double strength.

2. Dispense in test tubes containing Durham tubes.

3. Autoclave at 121°C for 15 minutes.

4. Test samples of the finished product for performance using stable, typical control cultures.

Identification Specification and Cultural Response

Dehydrated Appearance:	Light beige, free-flowing, homogeneous.
Prepared Appearance: Solution:	Purple, clear. 3.5% solution, soluble in purified water. Solution is purple, clear.
pH:	7.3 ± 0.1
Cultural Response:	Prepare the medium per label directions. Inoculate and incubate at 35 ± 2°C for 18-24 hours.
Reaction	3.5%
Solution	25°C

Microorganism	ATCC	CFU	Recovery
Enterococcus faecalis	29212	103-2×103	Markted to complete inhibition
Escherichia coli	25922	102-103	Good
Salmonella choleraesuis subsp. choleraesuis serotype Choleraesuis var. kunzendorf	12011	102-103	Good

Expected Results

Lactose-fermenting organisms grow very well in MacConkey Broth and produce acid, causing the medium to turn yellow. Gas is also produced, which collects in the Durham tubes. Nonfermenting organisms produce good growth but will not produce acid or gas.

References

1. MacConkey. 1901. Zentralbl. Bakteriol. 29:740.

2. MacConkey. 1905. J. Hyg. 5:333.

3. MacConkey. 1908. J. Hyg. 8:322.

4. Childs and Allen. 1953. J. Hyg. Camb. 51:468

Additional information

Size	9mL, 90mL, Custom

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MacConkey Broth

MacConkey Broth

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