Category: Stock solution
Preparation of SOB (Super Optimal Broth) Medium
SOB (Super Optimal Broth) medium is a nutrient-rich microbial growth medium, designed by Douglas Hanahan in 1983. SOB or its glucose-supplemented version SOC is often used during transformation of E. coli competent cells with plasmids (added in transformed cells after heat shock). It results in better survival and higher transformation efficiency as compared to regular LB medium. It contains 2% Bacto-tryptone, 0.5% Bacto-yeast extract, 0.05% Sodium chloride, 2.5 mM KCl, and 10 mM MgCl2. A 1000 ml SOB medium is prepared by dissolving 20 g bacto-tryptone, 5 g bacto-yeast extract, 0.5 g sodium chloride and 2.5 ml of 1M KCl in water to a final volume of 1000 ml. Medium is sterilized by autoclaving. MgCl2 (5 ml of 2M MgCl2) is added just before use.
Preparation of 10 M Sodium Hydroxide (NaOH) Solution
Here we have described a procedure to prepare 10 M (or 10 N) sodium hydroxide (NaOH) solution. A 10 M NaOH solution can be prepared by dissolving 40 g of NaOH (Molecular Weight: 40.00) in water to a final volume of 100 ml. Since dissolution of NaOH in water is a highly exothermic reaction, extreme care must be taken while preparing the solution.