Citizendia

An Agar Plate -- an example of a bacterial growth medium. Specifically, it is a streak plate; the orange lines and dots are formed by bacterial colonies.
An Agar Plate -- an example of a bacterial growth medium. Specifically, it is a streak plate; the orange lines and dots are formed by bacterial colonies.

A growth medium or culture medium is a liquid or gel designed to support the growth of microorganisms or cells. A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called [1] There are different types of media for growing different types of cells. [2]

There are two major types of growth media: those used for cell culture, which use specific cell types derived from plants or animals, and microbiological culture, which are used for growing microorganisms, such as bacteria or yeast. Cell culture is the process by which prokaryotic, or eukaryotic cells are grown under controlled conditions A microbiological culture, AKA microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described The most common growth media for microorganisms are nutrient broths and agar plates; specialized media are sometimes required for microorganism and cell culture growth. An agar plate is a sterile Petri dish that contains a Growth medium (typically Agar plus nutrients used to culture Microorganisms [1] Some organisms, termed fastidious organisms, require specialized environments due to complex nutritional requirements. Viruses, for example, are obligatory intracellular parasites and require a growth medium composed of living cells. Parasitism is a type of symbiotic relationship between Organisms of different Species.

Contents

Types of growth mediums

The most common growth mediums for microorganisms are nutrient broths (liquid nutrient medium) or Luria Bertani medium (LB medium or Lysogeny Broth). Lysogeny broth ( LB) a nutritionally rich medium, is primarily used for the growth of bacteria. Liquid mediums are often mixed with agar and poured into petri dishes to solidify. Agar or agar agar is a Gelatinous substance derived from Seaweed. A Petri dish is a shallow Glass or Plastic Cylindrical lidded dish that biologists use to culture cells It was named after These agar plates provide a solid medium on which microbes may be cultured. An agar plate is a sterile Petri dish that contains a Growth medium (typically Agar plus nutrients used to culture Microorganisms Bacteria grown in liquid cultures often form colloidal suspensions. A colloid is a type of mechanical Mixture where one substance is dispersed evenly throughout another In Chemistry, A suspension is a Heterogenous fluid containing Solid particles that are sufficiently large for Sedimentation.

The differences between growth mediums used for cell culture and those used for microbiological culture are due to the fact that cells derived from whole organisms and grown in culture often cannot grow without the addition of, for instance, hormones or growth factors which usually occur in vivo. Hormones (from Greek ὁρμή - "impetus" are chemicals released by cells that affect cells in other parts of the body The term growth factor refers to a naturally occurring Protein capable of stimulating cellular growth proliferation and Cellular differentiation. In vivo ( Latin: within the living means that which takes place inside an organism. [3] In the case of animal cells, this difficulty is often addressed by the addition of blood serum to the medium. Blood plasma is the Liquid component of Blood, in which the Blood cells are suspended In the case of microorganisms, there are no such limitations, as they are often unicellular organisms. A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually One other major difference is that animal cells in culture are often grown on a flat surface to which they attach, and the medium is provided in a liquid form, which covers the cells. In contrast, bacteria such as Escherichia coli may be grown on solid media or in liquid media.

An important distinction between growth media types is that of defined versus undefined media. [1] A defined medium will have known quantities of all ingredients. For microorganisms, they consist of providing trace elements and vitamins required by the microbe and especially a defined carbon source and nitrogen source. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Glucose or glycerol are often used as carbon sources, and ammonium salts or nitrates as inorganic nitrogen sources). Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Ammonium is also an old name for the Siwa Oasis in western Egypt. Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants In Inorganic chemistry, a nitrate is a salt of Nitric acid with an Ion composed of one Nitrogen and three Oxygen atoms Traditionally inorganic compounds are considered to be of mineral not biological origin An undefined medium has some complex ingredients, such as yeast extract or casein hydrolysate, which consist of a mixture of many, many chemical species in unknown proportions. Yeast extract is the common name for various forms of processed Yeast products that are used as food additives or flavourings Undefined media are sometimes chosen based on price and sometimes by necessity - some microorganisms have never been cultured on defined media.

A good example of a growth medium is the wort used to make beer. WORT (899 FM is a listener-sponsored community radio station broadcasting from 118 S Beer is the world's oldest and most widely consumed Alcoholic beverage and the third most popular drink overall after water and tea The wort contains all the nutrients required for yeast growth, and under anaerobic conditions, alcohol is produced. When the fermentation process is complete, the combination of medium and dormant microbes, now beer, is ready for consumption. Fermentation in Food processing typically refers to the conversion of Sugar to Alcohol using Yeast under Anaerobic conditions

Nutrient media

An undefined medium (also known as a basal or complex medium) is a medium that contains:

This is an undefined medium because the amino acid source contains a variety of compounds with the exact composition being unknown. Nutrient media contain all the elements that most bacteria need for growth and are non-selective, so they are used for the general cultivation and maintenance of bacteria kept in laboratory culture collections.

Defined media (also known as chemically defined media)

Differential medium

Minimal media

Minimal media are those that contain the minimum nutrients possible for colony growth, generally without the presence of amino acids, and are often used by microbiologists and geneticists to grow "wild type" microorganisms. Minimal media can also be used to select for or against recombinants or exconjugants. Bacterial conjugation is the transfer of genetic material between bacteria through direct cell-to-cell contact

Minimal medium typically contains:

Supplementary minimal media are a type of minimal media that also contains a single selected agent, usually an amino acid or a sugar. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Succinic acid ( IUPAC Systematic name: butanedioic acid; historically known as spirit of amber) is a Dicarboxylic acid. Magnesium (mægˈniːziəm is a Chemical element with the symbol Mg, Atomic number 12 Atomic weight 24 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl A nucleic acid is a Macromolecule composed of chains of monomeric Nucleotides In Biochemistry these Molecules carry Genetic information In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. This supplementation allows for the culturing of specific lines of auxotrophic recombinants. Auxotrophy is the inability of an organism to synthesize a particular Organic compound required for its growth (as defined by IUPAC)

Selective media

Blood-free, charcoal-based selective medium agar (CSM) for isolation of Campylobacter.
Blood-free, charcoal-based selective medium agar (CSM) for isolation of Campylobacter. The Genus Campylobacter, (meaning 'twisted bacteria' first discovered in 1963 describes Gram-negative, spiral Microaerophilic bacteria
Blood agar plates are often used to diagnose infection. On the right is a positive Streptococcus culture; on the left a positive Staphylococcus culture.
Blood agar plates are often used to diagnose infection. On the right is a positive Streptococcus culture; on the left a positive Staphylococcus culture. Streptococcus is a Genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the Staphylococcus (in Greek σταφυλη staphyle means bunch of grapes and κοκκος coccos means granule is a genus of Gram-positive

Selective mediums are used for the growth of only select microorganisms. For example, if a microorganism is resistant to a certain antibiotic, such as ampicillin or tetracycline, then that antibiotic can be added to the medium in order to prevent other cells, which do not possess the resistance, from growing. In modern usage an antibiotic is a Chemotherapeutic agent with activity against Microorganisms such as Bacteria, fungi or Protozoa Ampicillin is a beta-lactam Antibiotic that has been used extensively to treat bacterial Infections since 1961 This article deals with the specific antibiotic called tetracycline Media lacking an amino acid such as proline in conjunction with E. coli unable to synthesize it were commonly used by geneticists before the emergence of genomics to map bacterial chromosomes. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Proline (abbreviated as Pro or P) is an α- Amino acid, one of the twenty DNA -encoded amino acids Genomics is the study of an organism's entire Genome. The field includes intensive efforts to determine the entire DNA sequence of organisms and fine-scale Genetic

Selective growth media are also used in cell culture to ensure the survival or proliferation of cells with certain properties, such as antibiotic resistance or the ability to synthesize a certain metabolite. Cell culture is the process by which prokaryotic, or eukaryotic cells are grown under controlled conditions Antibiotic resistance is the ability of a Microorganism to withstand the effects of Antibiotics. Metabolomics is the "systematic study of the unique chemical fingerprints that specific cellular processes leave behind" - specifically the study of their small-molecule metabolite Normally, the presence of a specific gene or an allele of a gene confers upon the cell the ability to grow in the selective medium. History See also History of genetics The existence of genes was first suggested by Gregor Mendel (1822-1884 who in the 1860s studied inheritance An allele (ˈæliːl (UK /əˈliːl/ (US (from the Greek αλληλος allelos, meaning each other) is one member of a pair or series of different forms In such cases, the gene is termed a marker. A genetic marker is a known DNA sequence. It can be described as a variation which may arise due to mutation or alteration in the genomic loci that can be observed

Selective growth media for eukaryotic cells commonly contain neomycin to select cells that have been successfully transfected with a plasmid carrying the neomycin resistance gene as a marker. Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex Neomycin is an Aminoglycoside Antibiotic that is found in many topical medications such as creams ointments and eyedrops Transfection is the process of introducing nucleic acids into cells by non-viral methods. Gancyclovir is an exception to the rule as it is used to specifically kill cells that carry its respective marker, the Herpes simplex virus thymidine kinase (HSV TK). Herpes simplex virus 1 and 2 ( HSV-1 and HSV-2) are two species of the herpes virus family Herpesviridae, which cause infections

Four types of agar plates demonstrating differential growth depending on bacterial metabolism.
Four types of agar plates demonstrating differential growth depending on bacterial metabolism.

Some examples of selective media include:

Differential media

Differential media or indicator media distinguish one microorganism type from another growing on the same media. Methylene blue is a heterocyclic aromatic Chemical compound with Molecular formula: C 16 H 18 Cl[[nitrogen Gram-positive bacteria are those that are stained dark blue or violet by Gram staining. Gram-negative bacteria are those Bacteria that do not retain Crystal violet dye in the Gram staining protocol Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described WikipediaManual_of_Style#National_varieties_of_English --> Molds (or pH is the measure of the acidity or alkalinity of a Solution. An agar plate is a sterile Petri dish that contains a Growth medium (typically Agar plus nutrients used to culture Microorganisms The group A streptococcus bacterium ( Streptococcus pyogenes, or GAS) is a form of Streptococcus bacteria responsible for most cases Streptococcus is a Genus of spherical Gram-positive bacteria belonging to the phylum Firmicutes and the Proteus McConkeyjpg|thumb|right|200px|A MacConkey agar plate with an active bacterial culture Gram-negative bacteria are those Bacteria that do not retain Crystal violet dye in the Gram staining protocol Buffered charcoal yeast extract (BCYE Agar is a selective growth medium used to culture or grow certain Bacteria, particularly the Gram-negative Legionella pneumophila is a thin pleomorphic, Flagellated Gram-negative bacterium of the genus Legionella. [4] This type of media uses the biochemical characteristics of a microorganism growing in the presence of specific nutrients or indicators (such as neutral red, phenol red, eosin y, or methylene blue) added to the medium to visibly indicate the defining characteristics of a microorganism. Neutral Red (or toluylene red, Basic Red 5, or CI 50040) is a Eurhodin dye used for Staining in Histology. Phenol red (also known as phenolsulfonphthalein or PSP) is a PH indicator that is frequently used in Cell biology laboratories Eosin is a Fluorescent red Dye resulting from the action of Bromine on Fluorescein. Methylene blue is a heterocyclic aromatic Chemical compound with Molecular formula: C 16 H 18 Cl[[nitrogen This type of media is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria.

Examples of differential media include:

Transport media

These are used for the temporary storage of specimens being transported to the laboratory for cultivation. Eosin methylene blue ( EMB) is a selective stain for Gram-negative bacteria. Proteus McConkeyjpg|thumb|right|200px|A MacConkey agar plate with an active bacterial culture The lac operon is an Operon required for the transport and Metabolism of Lactose in Escherichia coli and some other Such media ideally maintain the viability of all organisms in the specimen without altering their concentration. Transport media typically contain only buffers and salt. The lack of carbon, nitrogen, and organic growth factors prevents microbial multiplication. Transport media used in the isolation of anaerobes must be free of molecular oxygen. Example :stuart transport medium.

Enriched media

Enriched media contain the nutrients required to support the growth of a wide variety of organisms, including some of the more fastidious ones. They are commonly used to harvest as many different types of microbes as are present in the specimen. Blood agar is an enriched medium in which nutritionally rich whole blood supplements the basic nutrients. An agar plate is a sterile Petri dish that contains a Growth medium (typically Agar plus nutrients used to culture Microorganisms Chocolate agar is enriched with heat-treated blood (40-45°C), which turns brown and gives the medium the color for which it is named. Chocolate agar (CHOC - is a non-selective enriched Growth medium.

See also

References

  1. ^ a b c Madigan M, Martinko J (editors). R2A agar is a Culture medium developed to study Bacteria which normally inhabit potable water Often abbreviated to MRS, this type of bacterial Growth medium is so-mamed by its inventors de Man Rogosa and Sharp See also List of basic cell biology topics. Cell biology (also called cellular biology or formerly cytology, from the (2005). Brock Biology of Microorganisms, 11th ed. , Prentice Hall. ISBN 0131443291.  
  2. ^ Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology, 4th ed. , McGraw Hill. ISBN 0838585299.  
  3. ^ Cooper GM (2000). "Tools of Cell Biology", The cell: a molecular approach. Washington, D. C: ASM Press. ISBN 0-87893-106-6.  
  4. ^ Washington JA (1996). "Principles of Diagnosis", Baron's Medical Microbiology (Baron S et al, eds.), 4th ed. , Univ of Texas Medical Branch. ISBN 0-9631172-1-1.  

External links

Dictionary

growth medium

-noun

  1. (microbiology) A culture medium.
© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic