MacCONKEY Broth

MacCONKEY Broth

EMD Cat. No. 1.05396.0500

500 g

Selective culture medium used as a presumptive test for E. coli and coliform bacteria and for determining the E. coli or coliform titre of milk, water and other materials according to MacCONKEY and HILL (1901).

This medium largely complies with the European Pharmacopeia 6 and United States Pharmacopeia 30.

Click here for information about harmonization of USP/EP chapters on Microbiological Examination of Non-sterile Products (formerly called Microbial Limits Test).

Additives

Mode of Action	Preparation
Experimental Procedure and Evaluation	Quality Control
Typical Composition (g/liter)	Literature

ChemDat®

Mode of Action
This broth contains lactose which, when degraded, gives acid and gas, according to the definition indicating the presence of E. coli. The gas formed is collected in DURHAM tubes and acid production is detected by the indicator bromocresol purple, which turns yellow. Ox bile promotes the growth of several species of intestinal bacteria and inhibits that of microorganisms, which do not inhabit the intestine.

Typical Composition (g/liter):
Peptone from gelatin 20.0; lactose 10.0; ox bile, dried 5.0' bromocresol purple 0.01.

Preparation

Suspend 35 g/liter or more (see Table below) in purified water, fill into test tubes, if desired insert DURHAM tubes, autoclave
(15 min at 121 °C).

pH: 7.3 + 0.2 at 25 °C.
The prepared broth is clear and purple.

Experimental Procedure and Evaluation
Mix 1, 10 or 100 ml samples with the specified volumes of MaConkey broth. The initial concentrration of the MaConkey broth must be increased so that the final concentration of the components is maintained at a constant level (35 g/l). See table.

Inoculum (ml)	Amount of Medium in Tube ml	Volume of Medium + Inoculum ml	Dehydrated Lactose Broth Required g/L	Broth Concentration
1	10 or more	11 or more	35	1-fold
10	10	20	70	<2-fold/font>
10	20	30	52.5	1.5-fold
100	20	120	210	6-fold
100	50	150	105	3-fold

Incubation: 48 hours at 35 °C.
Check the DURHAM tubes for gas production.

Gas and acid are produced:	suggests E. coli and possibly other coliform bacteria
Only acid is produced:	suggests coliform bacteria without E. coli

Quality control

Test strains	Inoculum (cfu/ml)	Growth	color change to yellow	Gas formation
Escherichia coli ATCC 25922	10 - 100	good / very good	+	+
Escherichia coli ATCC 8739	10 - 100	good / very good	+	+
Enterobacter cloacae ATCC 13047	10 - 100	good / very good	+	+
Klebsiella pneumoniae ATCC 13883	10 - 100	good / very good	+	+
Proteus mirabilis ATCC 14273	10 - 100	good / very good	-	-
Pseudomonas aeruginosa ATCC 27853	10 - 100	fair	-	-
Staphylococcus aureus ATCC 6538	≥100	fair	-	-

Literature

MacCONKEY, A.: Bile salt media and their advantages in some bacteriological examinations. J. Hyg., 8; 322-334 (1908).
MacCONKEY, A.: Lactose-fermenting bacteria in faeces. J. Hyg., 8; 333-379 (1905).
Deutsches Arzneibuch DAB 10.
MacCONKEY, A., a. HILL: Bile salt broth. Thompson Yates Lab. Rep., VI/1; 151 (1901) (zitiert in MacCONKEY, 1905).

United States Pharmacopeia 30

<61> Microbiological Examination of Non-sterile Products: Microbial Enumeration Tests (USP 30, page 89).
<62> Microbiological Examination of Non-sterile Products: Tests for Specified Microorganisms (USP 30, page 93).

European Pharmacopeia 6 (Ph. Eur)
2.6.12 Microbiological Harmonization of Non-sterile Products - Microbial Enumeration Test
2.6.12 Microbiological Harmonization of Non-sterile Products - Tests for Specified Microorganisms