SCHAEDLER AGAR
For recovery and cultivation of anaerobic microorganisms
5771
Schaedler Agar is based on CASO Broth / Trypticasein Soy Broth (X938).
Approximate formula in g/l:
Casein peptone .................................................................. 5,66
Soy peptone .......................................................................... 1,0
Sodium chloride .................................................................. 1,66
Dipotassium hydrogen phosphate ...................................... 0,83
Peptone mixture .................................................................... 5,0
Yeast extract ........................................................................ 5,0
Glucose .............................................................................. 5,83
Tris ....................................................................................... 3,0
L-Cystine .............................................................................. 0,4
Hemin ................................................................................ 0,01
Agar ................................................................................... 13.5
pH value ................................................................... 7,6 ± 0,2
PREPARATION
Suspend 41.9 g of the medium in one liter of distilled or deionised water. Mix well. Heat slowly until the medium is dissolved.
Cool to 45 - 50°C and, if desired, add 5 % sterile defibrinated blood. Homogenize gently and pour into Petri dishes.
Be careful to avoid bubble formation when adding the blood. The medium is slightly opalescent and beige or red
(with supplemented blood).
USES
Schaedler Agar is prepared according to the formulation described by Schaedler and coworkers1, as modified by Mata et
al.2. Due to its superior nutritive properties and its low oxidation-reduction potential the medium can easily support the
growth of fastidious anaerobes from the intestinal and digestive tracts and other internal organs.
Under standard conditions, proliferation of anaerobes is diminished by the rapid increase of Enterococcus, Escherichia
coli, Enterobacter, and other intestinal facultative anaerobic bacteria. In Schaedler media, cystine plus dextrose is used to
lower the oxidation-reduction potential and specifically support growth of anaerobic organisms, since the widely used
thioglycollate has shown inhibitory potential to some anaerobic microorganisms.
We recommend consulting methods for the cultivation of anaerobic organisms in food analysis. Suspend a determined
amount of the sample in a known volume of physiological saline. Take 1 ml for preparation of serial dilutions. With a
calibrated loop inoculate duplicate plates, previously dried, and incubate for the appropriate time and temperature valid for
the type of culture under test. For enumeration, select those plates that contain 30 to 100 colonies.
Schaedler Agar can also be used for the isolation and recovery of anaerobic bacteria from faeces and contents of the
intestinal tract by adding selective substances as given in brackets: Lactobacillus and Streptococcus (NaCl 10 g/l,
Neomycin 2 mg/l, Art. No. 8668), Clostridium and Bacteroides (placenta powder 2 g/l, Neomycin 2 mg/l),
Flavobacterium
(7 ml/l tyrothricin 0.5 % in ethanol). Incubate anaerobically at 35 °C.
Note: When using Schaedler Agar without blood, strict anaerobic conditions have to be implemented for detection of
obligate anaerobes.
MICROBIOLOGICAL TEST
The following results were obtained in the performance of the given medium from type cultures after incubation under
anaerobic conditions at a temperature of 35±2 °C and observed after 24-48 hours.