# calculation problem in media preparation - media preparation (May/29/2007 )

Hi, i have to make basal medium(MRS) with the following ingredients (g per l): peptone from casein (10.0g),
yeast extraxt (4.0g), Tween 80 (1.0ml), K2HPO4 (2.0g), (NH4)2 citrate (2.0g), sodium acetate
(5.0g), MgSO4 (0.2g), MnSO4 (0.02g), pH 6.2. Then later 16 ml of basal media were tranfered to each test tubes. After that, each tubes were supplemented with carbohydrate and make it up the carbohyrate concentration to 1% (W/V) in the 16 ml basal media. How to do the calculation to make sure the ingredient concentration of basal media is not varied after i supplemented with 1% of carbohyrate in test tube. Then i have to make sure the carbohydrate concentration is 1% after i spike in to the 16 ml basal media. The concentration of stock (carbohyrate) i prepared were 3.0g/10 ml

-saminathan-

QUOTE (saminathan @ May 29 2007, 07:35 PM)
Hi, i have to make basal medium(MRS) with the following ingredients (g per l): peptone from casein (10.0g),
yeast extraxt (4.0g), Tween 80 (1.0ml), K2HPO4 (2.0g), (NH4)2 citrate (2.0g), sodium acetate
(5.0g), MgSO4 (0.2g), MnSO4 (0.02g), pH 6.2. Then later 16 ml of basal media were tranfered to each test tubes. After that, each tubes were supplemented with carbohydrate and make it up the carbohyrate concentration to 1% (W/V) in the 16 ml basal media. How to do the calculation to make sure the ingredient concentration of basal media is not varied after i supplemented with 1% of carbohyrate in test tube. Then i have to make sure the carbohydrate concentration is 1% after i spike in to the 16 ml basal media. The concentration of stock (carbohyrate) i prepared were 3.0g/10 ml

stock of carbohyrate is 3.0g/10 ml, equally to 30X,

You can prepare stock of medium at 2X, then you can make a final medium with:

150 ml of stock of medium at 2X,
10 ml of stock of carbohyrate
140 ml water

-ngtienhuy-

QUOTE (ngtienhuy @ May 29 2007, 09:53 PM)
QUOTE (saminathan @ May 29 2007, 07:35 PM)
Hi, i have to make basal medium(MRS) with the following ingredients (g per l): peptone from casein (10.0g),
yeast extraxt (4.0g), Tween 80 (1.0ml), K2HPO4 (2.0g), (NH4)2 citrate (2.0g), sodium acetate
(5.0g), MgSO4 (0.2g), MnSO4 (0.02g), pH 6.2. Then later 16 ml of basal media were tranfered to each test tubes. After that, each tubes were supplemented with carbohydrate and make it up the carbohyrate concentration to 1% (W/V) in the 16 ml basal media. How to do the calculation to make sure the ingredient concentration of basal media is not varied after i supplemented with 1% of carbohyrate in test tube. Then i have to make sure the carbohydrate concentration is 1% after i spike in to the 16 ml basal media. The concentration of stock (carbohyrate) i prepared were 3.0g/10 ml

stock of carbohyrate is 3.0g/10 ml, equally to 30X,

You can prepare stock of medium at 2X, then you can make a final medium with:

150 ml of stock of medium at 2X,
10 ml of stock of carbohyrate
140 ml water

Thanks alot

-saminathan-