DEV LACTOSE PEPTONE BROTH
CAT Nº: 1420
For the enrichment and detection of coliforms in water
according to German standard methods.
FORMULA IN g/l
Meat Peptone
17.00
Soy Peptone
3.00
Lactose
10.00
Bromocresol Purple
0.02
Sodium Chloride
5.00
Final pH 7.2 ± 0.2 at 25ºC
PREPARATION
Suspend 35 grams of the medium in one liter of distilled water (or 70.0 grams if a double concentration is desired) .Mix
well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into tubes
with Durham gas collecting tubes for gas detection. and sterilize in autoclave at 121°C for 15 minutes. The prepared
medium should be stored at 2-8°C. The color of the prepared medium is purple.
The dehydrated medium should be homogeneous, free-flowing and beige in color. If there are any physical changes,
discard the medium.
USES
DEV LACTOSE PEPTONE BROTH is employed for the enrichment and determining the titre of coliform bacteria in the
bacteriological analysis of water according to the German Standard Methods for the examination of water and the
German drinking water regulations (1990).
Meat peptone and soy peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Lactose is the
fermentable carbohydrate providing carbon and energy. Sodium chloride supplies essential electrolytes for transport and
osmotic balance. Bromocresol purple is the pH indicator.
All coliforms ferment lactose with acid and gas production. This group includes the genera Escherichia, Enterobacter,
Citrobacter, and Klebsiella. When lactose is fermented it produces acid that changes the color of the medium from bluepurple (alkaline) to yellow (acid).
According to the German Methods, the inoculated broth is incubated for 44 ± 4 horas a 35ºC. If lactose-positive
microorganisms grow, the broth colour changes to yellow.
MICROBIOLOGICAL TEST
The following results were obtained from type cultures in the performance of the medium after incubation at a
temperature of 35ºC and observed after 44±4 hours.
Growth
Medium color
Gas production
Escherichia coli ATCC 25922
Good
+
+
Klebsiella pneumonia ATCC 13883
Good
+
+
Salmonella typhimurium ATCC 14028
Good
-
-
Aeromonas hydrophila ATCC 7966
Good
-
-
Enterococcus faecalis ATCC 11700
Good
±
-
Microorganisms
1
LABORATORIOS CONDA, S.A.
www.condalab.com
BIBLIOGRAPHY
Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung. - VCH Verlagsgesellschaft, D-6940 Weinheim.
Verordnung über Trinkwasser und über Wasser für Lebensmittelbetriebe vom 12. Dezember 1990. - Bundesgesetzbl., Teil I; 26132629 (1990).
STORAGE
25ºC
Once opened keep powdered medium closed to avoid hydration.
2ºC
2
LABORATORIOS CONDA, S.A.
www.condalab.com