Cetrimide Broth

Products
Media
Wallerstein Nutrient Broth (WL) and WL Differential Broth (WLD)
Wallerstein Nutrient Broth (WL) and
WLDifferential Broth (WLD)
WL Nutrient broth is used for the
determination of microbiological flora
in brewing and fermentation processes.
WL differential media suppresses
the growth of yeast and mold
and cultivated bacteria encountered
in brewing and industrial fermentation.
The medium has the same
formulation as WL nutrient media but
has 4 mg of Cyclohexamide per liter
added.
Description:
Use of the medium at pH 5.5 and
incubation at 25° C will give reliable
counts for brewer’s yeast. Adjustment
of the pH to 6.5 and incubation at 30° C
allows for the selective growth of
bakers and distillers yeast.
Interpretation WL Nutrient Broth:
Media will develop all yeast that
incubate at the selected temperature
and pH range.
WL Nutrient Broth
Organisms
Characteristics
Escherichia coli ATCC 25922Growth
L. fermentum ATCC 9338 Growth
S. cerevisiae ATCC 9763 Growth
Interpretation WL Differential Broth:
When incubated at pH 5.5 estimates of
beer cocci and lactic rods can be made
under anaerobic conditions. Estimates
of acetic acid rods and thermobacteria
are made under aerobic conditions.
WL Differential Broth
Organisms
Characteristics
Escherichia coli ATCC 25922Growth
L. fermentum ATCC 9338 Growth
S. cerevisiae ATCC 9763 Partial to marked inhibition
Quality Control and recommended
incubation conditions WL Nutrient:
Positive control:
Sacchromyces cerivisiae ATCC 4098,
incubated 48 hours at 25–30° C.
Escherichia coli ATCC 25922,
incubated 24–48 hours at 35° C.
Negative control:
Not applicable.
Sterility:
7 days plated sterility test.
Quality Control and recommended
incubation conditions WL Differential:
Positive control:
Lactobacillus plantarum ATCC 8014,
incubated 48 hours at 35° C.
Negative control:
Sacchromyces cerivisiae ATCC 4098,
incubated 48 hours at 25–30° C.
Sterility:
7 days plated sterility test.
Culture of Sacchromyces cerivisiae ATCC 4098 on
Wallerstein Nutrient Broth (WL).
Formulation:
Per liter of water adjusted
to pH 5.5 ± 0.2
Casein
Yeast Extract
Dextrose
Monopotassium phospate
Potassium chloride
Calcium chloride
Magnesium sulfate
Ferric chloride
Manganese sulfate
Bromocresol green
Additional Component
for WL Differential Broth:
Cyclohexamide
5.0 g
4.0 g
50.0 g
550 mg
425 mg
125 mg
125 mg
2.5 mg
2.5 mg
22 mg
4 mg
Additional information:
WL Nutrient Broth has a pH of 5.5 which is optimal for the enumeration of
brewers’ yeast. In the case of cultivating microorganisms from an alcoholic
mash, tomato juice should be added to the medium. WL Differential Media
contains additionally 4 mg of Cyclohexamide per liter. This component
inhibits the developments of yeast without interfering with the development
of bacteria generally encountered in beers. Cyclohexamide in WL Differential
Broth is added to suppress yeast and any mold which may be
present.
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