Super Optimal Broth (SOB medium) is a

nutrient A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

-rich bacterial

growth medium A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation or small plants like the moss ''Physcomitrella patens''. Differe ...

used for

microbiological culture A microbiological culture, or microbial culture, is a method of multiplying microorganism, microbial organisms by letting them reproduce in predetermined culture medium under controlled laboratory conditions. Microbial cultures are foundational a ...

, generally of ''

Escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...

''. This nutrient-rich microbial

broth Broth, also known as bouillon (), is a savory liquid made of water in which meat, fish, or vegetables have been simmered for a short period of time. It can be eaten alone, but it is most commonly used to prepare other dishes, such as soups ...

contains

peptides Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Dalton (unit), Da or more are called proteins. Chains of fewer t ...

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

s, water soluble

vitamins Vitamins are organic molecules (or a set of closely related molecules called vitamers) that are essential to an organism in small quantities for proper metabolic function. Essential nutrients cannot be synthesized in the organism in suff ...

and

glucose Glucose is a sugar with the Chemical formula#Molecular formula, molecular formula , which is often abbreviated as Glc. It is overall the most abundant monosaccharide, a subcategory of carbohydrates. It is mainly made by plants and most algae d ...

in a low-salt formulation. It was developed by

Douglas Hanahan Douglas Hanahan (born 1951) is an American biologist, professor, and Director Emeritus of the Swiss Institute for Experimental Cancer Research at EPFL (École polytechnique Fédérale de Lausanne) in Lausanne, Switzerland. He is a Distinguishe ...

in 1983 and is an adjusted version of the commonly used LB medium (

lysogeny broth Lysogeny broth (LB) is a Nutrient, nutritionally rich Growth medium, medium primarily used for the Bacterial growth, growth of bacteria. Its creator, Giuseppe Bertani, intended LB to stand for lysogeny broth, but LB has also come to colloquially ...

). Growth of ''

E. coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escherichia'' that is commonly foun ...

'' in SOB or SOC medium results in higher

transformation Transformation may refer to: Science and mathematics In biology and medicine * Metamorphosis, the biological process of changing physical form after birth or hatching * Malignant transformation, the process of cells becoming cancerous * Trans ...

efficiencies of

plasmid A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria and ...

s.SOC Medium
/ref> SOC medium can also be used to regenerate '' Klebsiella oxytoca'' strains for the improved transformation efficiency. Super Optimal broth with Catabolite repression (SOC) is SOB with

added to the culture medium as preferred carbon and energy source (''i.e.'', rapidly metabolizable).http://www.protocol-online.org/biology-forums/posts/10626more1.html

Composition

Figures in parentheses are the masses of reagents required to prepare 1 liter of medium.

SOB

* 2 % w/v

tryptone Tryptone is the assortment of peptides formed by the digestion of casein by the protease trypsin. Tryptone is commonly used in microbiology to produce lysogeny broth, lysogeny broth (LB) for the growth of ''Escherichia coli, E. coli'' and other m ...

( tryptic peptides from the

casein Casein ( , from Latin ''caseus'' "cheese") is a family of related phosphoproteins (CSN1S1, αS1, aS2, CSN2, β, K-casein, κ) that are commonly found in mammalian milk, comprising about 80% of the proteins in cow's milk and between 20% and 60% of ...

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

trypsin Trypsin is an enzyme in the first section of the small intestine that starts the digestion of protein molecules by cutting long chains of amino acids into smaller pieces. It is a serine protease from the PA clan superfamily, found in the dig ...

) (20 g) * 0.5 % w/v

yeast extract Yeast extracts consist of the cell contents of yeast without the cell walls; they are used as food additives or flavorings, or as nutrients for bacterial culture Growing media, media. They are often used to create savoury flavors and umami tast ...

(5 g) * 8.56 mM

NaCl Sodium chloride , commonly known as edible salt, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral hali ...

(0.5 g) or 10 mM NaCl (0.584 g) * 2.5 mM KCl (0.186 g) * Doubly distilled H₂O to 1000 mLSOC medium
/ref> * 10 mM MgCl₂ (anhydrous: 0.952 g; hexahydrate: 2.033 g) and 10 mM MgSO₄ (anhydrous:1.204 g; heptahydrate: 2.465 g)

SOC

In addition to the SOB contents, SOC also contains 20 mM

(3.603 g). Alternatively, SOB and SOC can be prepared by adding small amounts of concentrated magnesium chloride and glucose solutions to pre-prepared SOB.

pH adjustment

For maximum effectiveness, SOB/SOC media should have its pH adjusted to 7.0 by adding concentrated

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

. The original literature states that the pH of the final medium should be between 6.8 and 7.0.

Sterilization

Finally, the SOB medium should be

autoclave An autoclave is a machine used to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient pressure and/or temperature. Autoclaves are used before surgical procedures to perform steriliza ...

d at 121 °C to ensure sterility. The components of SOC medium should not be autoclaved together because at elevated temperature glucose can react with the tryptic peptides (see Maillard reaction), compromising the quality of the preparation. SOB and magnesium and glucose additive solutions can be autoclaved separately and mixed afterwards to the final concentrations. Complete SOC can be filter sterilized through a 0.22 μm filter.

References

{{Reflist Microbiological media American inventions