MRS Agar is a medium for the cultivation and enumeration of Lactobacillus spp.
Originally developed in 1960 by de Man, Rogosa & Sharpe, the medium is suitable for most lactic acid bacteria and is intended as a substitute for Tomato Juice Agar.
When acidified to pH 5.4 M.R.S. Agar can be used to enumerate Lactobacillus bulgaricus in yoghurts.
Nutrition is provided by a mixture of carefully selected peptones, glucose, beef & yeast extracts whilst Tween® 80, magnesium and manganese sulphates act as growth stimulants. Selectivity against streptococci & moulds is provided by ammonium citrate and sodium acetate. Used at low pH, ammonium citrate allows growth of lactobacilli whilst inhibiting a number of other organism groups.
Occasionally, sterilisation of this medium at 121oC for 15 minutes, in some autoclaves, may cause the pH to fall outside of the specified pH limits 6.4 +/- 0.2. In these rare cases, adjustment of the medium using acetic acid or sodium hydroxide is recommended.
MRS Agar is a medium for the cultivation and enumeration of Lactobacillus spp.Originally developed in 1960 by de Man, Rogosa & Sharpe, the medium is suitable for most lactic acid bacteria and is intended as a substitute for Tomato Juice Agar.When acidified to pH 5.4 M.R.S. Agar can be used to enumerate Lactobacillus bulgaricus in yoghurts.Nutrition is provided by a mixture of carefully selected peptones, glucose, beef & yeast extracts whilst Tween® 80, magnesium and manganese sulphates act as growth stimulants. Selectivity against streptococci & moulds is provided by ammonium citrate and sodium acetate. Used at low pH, ammonium citrate allows growth of lactobacilli whilst inhibiting a number of other organism groups.Occasionally, sterilisation of this medium at 121oC for 15 minutes, in some autoclaves, may cause the pH to fall outside of the specified pH limits 6.4 +/- 0.2. In these rare cases, adjustment of the medium using acetic acid or sodium hydroxide is recommended.
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