SOB Medium
Also known as：SOB · Super Optimal Broth · S.O.B. Medium · Hanahan's Broth
For the preparation and cultivation of competent Escherichia coli cells prior to transformation.
- Category
- Dehydrated Culture Media
- Pack sizes
- 500 g · 5 kg · 25 kg
- Certifications
- ISO 22000
Data updated：2026-11-06
Overview
Principle
SOB Medium is a nutrient-rich, low-salt medium developed by Hanahan for the growth of Escherichia coli during the preparation of competent cells.¹ Tryptone and yeast extract supply the nitrogen, amino acids, peptides, and vitamins required for rapid growth. The low sodium chloride content, together with potassium chloride, maintains the osmotic balance and membrane potential while avoiding the higher ionic strength of conventional media, which is unfavourable to the development of competence. Magnesium ions, supplied as magnesium sulphate, stabilise the cell wall and membrane and are essential for the uptake of plasmid DNA.¹ SOB Medium contains no added carbohydrate. Where a rapidly metabolizable carbon source is required for the recovery of cells after transformation, glucose is added to give SOC Medium.¹
Directions
Suspend 30.69 g of powder in 1 L of purified water. Heat with continuous stirring and bring to the boil for 1 minute. Dispense into tubes or flasks. Sterilize by autoclaving at 121°C for 15 minutes. Test the finished medium for performance using stable, standard control cultures.
Product highlights
- Food-grade raw materials, produced in an ISO 22000 certified facility
- Available in 500 g / 5 kg / 25 kg, from laboratory to industrial scale
- COA, specification sheet, and technical data sheet available; samples on request
- Manufactured in Taiwan with reliable supply
Food grade versus laboratory grade
Most culture media suppliers use laboratory-grade raw materials, which are held to lower standards for heavy metal residues, microbial contamination control, and traceability. That is adequate for pure research but not for applications with stricter raw-material requirements. STBIO manufactures with food-grade raw materials throughout, in a facility certified to ISO 22000 food safety management.
- Food microbiology laboratories working to ISO 17025 or equivalent requirements
- Biotech manufacturers exporting fermentation products and needing full raw-material traceability
- Organisations with ESG or compliance audit requirements across their supply chain
- Companies sourcing both Halal and non-Halal products who need one consistent material grade
Frequently asked questions
01Which organisms is it suitable for?
Gram-negative, Aerobes, E. coli. See the cultural response table and the specification sheet.
02Can it be used for food-grade applications?
Yes. It is made from food-grade raw materials in an ISO 22000 certified facility and is suitable for culturing starters for fermented products that are consumed directly.
03How is this product prepared?
Suspend 30.69 g of powder in 1 L of purified water. Heat with continuous stirring and bring to the boil for 1 minute. Dispense into tubes or flasks. Sterilize by autoclaving at 121°C for 15 minutes. Test the finished medium for performance using stable, standard control cultures.
04How do I request a bulk quotation, and can you provide a COA?
Yes. This product is available in 500 g, 5 kg, 25 kg. Tell us your application and volume when requesting a quotation; we reply within one working day and can supply the COA, specification sheet, and technical data sheet.
Used in these applications
References
- 1. Hanahan D., 1983. Studies on transformation of Escherichia coli with plasmids. J. Mol. Biol., 166(4):557-580.
- 2. Sambrook J. and Russell D. W., 2001. Molecular Cloning: A Laboratory Manual, 3rd Ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York.