SOB Broth, also known as Super Optimal Broth or Hanahan's Broth, is a nutrient-rich medium used for the cultivation and recovery of Escherichia coli. It is commonly used in molecular biology applications such as competent cell recovery, plasmid transformation, and recombinant DNA experiments.

Formulated with tryptone, yeast extract, salts, and magnesium ions, SOB Broth supports robust bacterial growth and efficient post-transformation recovery.

Hanahan, D. (1983). "Studies on transformation of Escherichia coli with plasmids". Journal of Molecular Biology. 166 (4): 557–580. 


Components Item g/L
Casein Enzymic Hydrolysate 20.00
Yeast Extract 5.00
Sodium Chloride 0.50
Magnesium Sulfate 2.40
Potassium Chloride 0.186

Final pH (at 25 °C) 7.0 ± 0.2

Suspend 28 grams of SOB Broth in 1000 mls of distilled water. Heat gently to dissolve the medium completely. Dispense in tubes and sterilize by autoclaving at 15 lbs. (121 °C) for 15 minutes.

Store at Room Temp.