MRS agar
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De Man–Rogosa–Sharpe agar, often abbreviated to MRS, is a selective culture medium designed to favour the luxuriant growth of Lactobacilli for lab study. Developed in 1960, this medium was named for its inventors, Johannes Cornelis de Man [Wikidata], Morrison Rogosa [Wikidata], and Margaret Elisabeth Sharpe [Wikidata]. It contains sodium acetate, which suppresses the growth of many competing bacteria (although some other Lactobacillales, like Leuconostoc and Pediococcus, may grow). This medium has a clear brown colour.[1]
Typical composition
MRS agar typically contains (w/v):[2]
- 1.0% peptone
- 1.0% beef extract
- 0.4% yeast extract
- 2.0% glucose
- 0.5% sodium acetate trihydrate
- 0.1% polysorbate 80 (also known as Tween 80)
- 0.2% dipotassium hydrogen phosphate
- 0.2% triammonium citrate
- 0.02% magnesium sulfate heptahydrate
- 0.005% manganese sulfate tetrahydrate
- 1.0% agar
- pH adjusted to 6.2 at 25 °C
The yeast/meat extracts and peptone provide sources of carbon, nitrogen, and vitamins for general bacterial growth. The yeast extract also contains vitamins and amino acids required by Lactobacilli. Polysorbate 80 is a surfactant which assists in nutrient uptake by Lactobacilli. Magnesium sulfate and manganese sulfate provide cations used in metabolism.
See also
- MacConkey agar (culture medium designed to grow Gram-negative bacteria and differentiate them for lactose fermentation).
References
- ^ EMD Chemicals, MRS Agar Archived 2009-04-30 at the Wayback Machine, 2002.
- ^ de Man, J.C.; Rogosa, M.; Sharpe, M.E. (1960). "A Medium for the Cultivation of Lactobacilli". Journal of Applied Bacteriology. 23 (1): 130–135. doi:10.1111/j.1365-2672.1960.tb00188.x.
- v
- t
- e
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