SOC medium
Encyclopedia
Super Optimal Broth is a nutrient
-rich bacterial growth medium
used for microbiological culture
, generally of Escherichia coli
. It was developed by Douglas Hanahan
in 1983 and is an adjusted version of the commonly used LB media (lysogeny broth
). Growth of E. coli in SOB or SOC medium results in higher transformation
efficiencies of plasmid
s.
Super Optimal broth with Catabolite repression
(SOC) is SOB with added glucose
.
Alternatively, SOC can be made by adding small amounts of concentrated magnesium chloride and glucose solutions to pre-prepared SOB.
adjusted to 7.0 by adding concentrated sodium hydroxide.
d at 121 °C to ensure sterility
. SOC medium should not be autoclaved because the high temperature can cause the glucose to react with tryptic peptides (see Maillard reaction
). SOC can instead be filter sterilized
through a 0.22 µm filter. Alternatively, SOB and magnesium and glucose additive solutions can be autoclaved separately and mixed afterwards to final concentrations, although any autoclaving may cause glucose to undergo caramelization
.
Nutrient
A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...
-rich bacterial growth medium
Growth medium
A growth medium or culture medium is a liquid or gel designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens.There are different types of media for growing different types of cells....
used for microbiological culture
Microbiological culture
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...
, generally of Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
. It was developed by Douglas Hanahan
Douglas Hanahan
Professor Douglas Hanahan an American biologist, and director of the Swiss Institute for Experimental Cancer Research.In 1983 he developed Super Optimal Broth, a microbiological growth medium....
in 1983 and is an adjusted version of the commonly used LB media (lysogeny broth
Lysogeny broth
Lysogeny broth , a nutritionally rich medium, is primarily used for the growth of bacteria. The acronym has been incorrectly interpreted as Luria broth, Lennox broth, or Luria-Bertani medium; according to its creator Giuseppe Bertani, the abbreviation LB was actually intended to stand for lysogeny...
). Growth of E. coli in SOB or SOC medium results in higher transformation
Transformation (genetics)
In molecular biology transformation is the genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material from its surroundings and taken up through the cell membrane. Transformation occurs naturally in some species of bacteria, but it can...
efficiencies of plasmid
Plasmid
In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular...
s.
Super Optimal broth with Catabolite repression
Catabolite repression
Carbon catabolite repression, or simply catabolite repression, is an important part of global control system of various bacteria and other micro-organisms. Catabolite repression allows bacteria to adapt quickly to a preferred carbon and energy source first...
(SOC) is SOB with added glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
.
SOB
- 2% w/v bacto-tryptoneTryptoneTryptone 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 for the growth of E. coli and other microorganisms...
(20 g) - 0.5% w/v bacto-yeast extract (5 g)
- 8.56mM NaCl (0.5 g) or 10mM NaCl (0.584 g)
- 2.5mM KClKCLKCL or KCl may stand for:*KCl, the chemical symbol for potassium chloride*Kirchhoff's current law*King's College London, constituent college of the University of London*Kyoto Common Lisp...
(0.186 g) - ddH2O to 1000 mL
SOC
In addition to the SOB contents, SOC also contains- 10mM MgCl2Magnesium chlorideMagnesium chloride is the name for the chemical compounds with the formulas MgCl2 and its various hydrates MgCl2x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine or sea water...
(0.952 g) or 20mM MgSO4Magnesium sulfateMagnesium sulfate is a chemical compound containing magnesium, sulfur and oxygen, with the formula MgSO4. It is often encountered as the heptahydrate epsomite , commonly called Epsom salt, from the town of Epsom in Surrey, England, where the salt was distilled from the springs that arise where the...
(2.408 g) - 20mM glucose (3.603 g)
Alternatively, SOC can be made 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 pHPH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
adjusted to 7.0 by adding concentrated sodium hydroxide.
Sterilization
Finally, the SOB medium should be autoclaveAutoclave
An autoclave is an instrument used to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C for around 15–20 minutes depending on the size of the load and the contents. It was invented by Charles Chamberland in 1879, although a precursor known as the...
d at 121 °C to ensure sterility
Sterilization (microbiology)
Sterilization is a term referring to any process that eliminates or kills all forms of microbial life, including transmissible agents present on a surface, contained in a fluid, in medication, or in a compound such as biological culture media...
. SOC medium should not be autoclaved because the high temperature can cause the glucose to react with tryptic peptides (see Maillard reaction
Maillard reaction
The Maillard reaction is a form of nonenzymatic browning similar to caramelization. It results from a chemical reaction between an amino acid and a reducing sugar, usually requiring heat....
). SOC can instead be filter sterilized
Microfiltration
Microfiltration is a membrane technical filtration process which removes contaminants from a fluid by passage through a microporous membrane. A typical microfiltration membrane pore size range is 0.1 to 10 micrometres...
through a 0.22 µm filter. Alternatively, SOB and magnesium and glucose additive solutions can be autoclaved separately and mixed afterwards to final concentrations, although any autoclaving may cause glucose to undergo caramelization
Caramelization
Caramelization is the browning of sugar, a process used extensively in cooking for the resulting nutty flavor and brown color. As the process occurs, volatile chemicals are released, producing the characteristic caramel flavor....
.