The medium complies with the German DIN-Norm 10109 and for the inspection of meat and to the regulations acc. to § 35 LMBG (06.00/35) for the inspection of food.
Mode of Action
The MRS culture media contain polysorbate, acetate, magnesium and manganese, which are known to act as special growth factors for lactobacilli, as well as a rich nutrient base. As these media exhibit a very low degree of selectivity, Pediococcus and Leuconostoc species and other secondary bacteria may grow on them.
Typical Composition (g/litre)
Peptone from casein 10.0; meat extract 8.0; yeast extract 4.0; D(+)-glucose 20.0; dipotassium hydrogen phosphate 2.0; Tween® 80 1.0; di-ammonium hydrogen citrate 2.0; sodium acetate 5.0; magnesium sulfate 0.2; manganese sulfate 0.04.
Suspend 52.2 g MRS Broth/litre, autoclave 15min at 121°C (or 15 min at 118 °C). Autoclavation at 118 °C result in better growth of Bifido bacterium spp.
pH: 5.7 ± 0.2 at 25 °C.
The broth filled into tubes are clear and brown.
Experimental Procedure and Evaluation
If necessary, homogenize the sample material and then transfer to MRS Broth for enrichment or for determining the bacterial count by the MPN method.
Incubation: up to 3 days at 35 °C or up to 5 days at 30 °C.
Determine the bacterial count. Identify the lactobacilli by the methods proposed by SHARPE (1962) and SHARPE et al. (1966).
For further methods of differentiation and identification see
ROGOSA et al. (1953), ROGOSA and SHARPE (1959) and DAVIS