Baird-Parker agar is a type of

agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from ogonori (''Gracilaria'') and "tengusa" (''Gelidiaceae''). As found in nature, agar i ...

used for the selective isolation of

gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

Staphylococci ''Staphylococcus'' is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical ( cocci), and form in grape-like clusters. ''Staphylococcus'' species are facultati ...

'' species. It contains

lithium chloride Lithium chloride is a chemical compound with the formula Li Cl. The salt is a typical ionic compound (with certain covalent characteristics), although the small size of the Li+ ion gives rise to properties not seen for other alkali metal chlorid ...

and

tellurite The tellurite ion is . A tellurite (compound), for example sodium tellurite, is a compound that contains this ion. They are typically colorless or white salts, which in some ways are comparable to sulfite. A mineral with the formula TeO2 is c ...

to inhibit the growth of alternative microbial flora, while the included

pyruvate Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is an intermediate in several metabolic pathways throughout the cell. Pyruvic a ...

and

glycine Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid ( carbamic acid is unstable), with the chemical formula NH2‐ CH2‐ COOH. Glycine is one of the proteinog ...

promote the growth of ''Staphylococci''. ''Staphylococcus'' colonies show up black in colour with clear zones produced around them.

History

Baird-Parker firstly publish an academic article about this agar medium for the purpose of improved diagnostic and isolating coagulase-positive ''Staphylococci'' in 1962. He developed this agar medium from the tellurite-glycine formulation of Zebovitz ''et al'' and improved its reliability in isolating coagulase-positive staphylococci from foods. Baird-Parker added egg yolk emulsion as a diagnostic agent and

sodium pyruvate Sodium pyruvate is a salt of the conjugate anion form of pyruvic acid, known as pyruvate. It is commonly added to cell culture media as an additional source of energy, but may also have protective effects against hydrogen peroxide. This was repor ...

to protect damaged cells and aid their recovery. It is now widely recommended by national and international bodies for the isolation of coagulase-positive ''staphylococci''. Braid-Parker agar is commonly use as a method for the enumeration of coagulase-positive staphylococci ('' Staphylococcus aureus'' and other species) in food and animal feeding stuffs.

Preparation and Formulae

The following is a method for the preparation of 1 litre of Baird-Parker agar according to ISO 11133:2014 and ISO 6888-1:1999. # Measure the following. These are the base of Baird-Parker agar. #* 10 gram of pancreatic digest of

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

#* 5 gram of

meat extract Meat extract is highly concentrated meat stock, usually made from beef or chicken. It is used to add meat flavour in cooking, and to make broth for soups and other liquid-based foods. Meat extract was invented by Baron Justus von Liebig, a Germ ...

#* 1 gram of

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 media. They are often used to create savory flavors and umami taste sensations, ...

#* 10 gram of sodium pyruvate #* 12 gram of L-glycine #* 5 gram of

#* 20 gram of agar # Suspend 63g of Baird-Parker Agar (ISO) Base in 1,000ml of distilled water. # Adust the pH into 7.2 ± 0.2 at 25°C. # Boil to dissolve the medium and sterilise by

autoclaving 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 ...

at 121°C for 15 minutes. # Cool to 47°C and aseptically add 50ml of Egg Yolk Tellurite Emulsion (SR0054). Mix well and pour into sterile Petri dishes. Dehydrated medium should be stored on 10-30°C. The prepared medium is best used freshly prepared. Dehydrated culture medium has straw coloured and free-flowing powder. Prepared medium has cream or yellow color, opaque gel.

References

Microbiology {{Microbiology-stub