SOC Medium

-Shake until solutes have dissolved and add:

*250mM KCl  10 ml (for 1 L)or 2 ml (for 200 ml)

-AdjustpH to 7 with 5 N NaOH (~ 0.2 ml), or 1 N NaOH.

-Adjustvolume to 1L or 200ml with deionized H₂O.

-Sterilizeby autoclaving for 20 min. at 15lb/sq. in. on liquid cycle.

-Allowmedium to cool to 60⁰C or less and then add18 ml(for 1 L)or 3.6 ml(for 200 ml) of 20 %  filter-sterilizedGlucose solution**.

-Add5 ml (for 1L) or 1 ml (for 200 ml) of a sterile solution of 2 M MgCl₂***.

Recipes

*250mMKCl: Dissolve 1.86g of KCl in 100ml of ddH₂O.

**20%Glucose:  Dissolve100 g of Glucose in 400 ml ddH₂O. After the sugar has dissolved complete the volume to 500 ml and sterilizethrough a 0.22-micron filter.

***2M MgCl₂:  Dissolve19 g of MgCl₂ in 90 ml ddH₂O. Adjust volume to 100 ml with ddH₂O and sterilize by autoclaving for 20 min. at 15 lb/sq. in. on liquid cycle. If you only have MgCl₂ x 6H₂O, then add 40.68 g ofthis to 90 ml ddH₂O.

This was found according to the followingcalculations:

For 100 ml 
2 M MgCl₂x 0.1 L= 0.2 mol

MW: (Mg=24.30, Cl=35.45,H=1.01, O=16.00)

MgCl₂ x 6H₂O = 203.31 g/mol 
MgCl₂ = 95.2 g/mol

95.2/203.31=0.468 
19g/0.468=40.68g

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