100mm diameter petri dishes containing agar jelly for bacterial culture

Agar or agar agar is a gelatinous substance chiefly used as a solid substrate to contain culture medium for microbiological work. It is an unbranched polysaccharide obtained from the cell membranes of some species of red algae, primarily from the genuses Gelidium and Gracilaria, or seaweed (Sphaerococcus euchema). Commercially it is derived primarily from Gelidium amansii. Agar is a thickening agent commonly used in microbiology. ... For the art collective, see Gelitin. ... For other uses, see Substrate. ... An Agar Plate -- an example of a bacterial growth medium. ... An agar plate streaked with microorganisms Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... The cell membrane (also called the plasma membrane, plasmalemma or phospholipid bilayer) is a selectively permeable lipid bilayer found in all cells. ... Possible classes Florideophyceae Bangiophyceae Cyanidiophyceae Red algae (Rhodophyta, pronounced /ˈrəʊdə(ʊ)ˌfʌɪtə/) are a large group of mostly multicellular, marine algae, including many notable seaweeds. ... For other uses, see Genus (disambiguation). ... Gracilaria is a genus of red algae (Rhodophyta) notable for its economic importance as an agarophyte, as well as its use as a food for humans and various species of shellfish. ... Ascophyllum nodosum exposed to the sun in Nova Scotia, Canada Dead Mans Fingers (Codium fragile) off Massachusetts coast For the band, see; Seaweed (band) For the rock musician, see; Seaweed (musician) Seaweeds are any of a large number of marine benthic algae. ...

Agar can be used as a laxative, a vegetarian gelatin substitute, a thickener for soups, in jellies, ice cream and Japanese desserts such as anmitsu, as a clarifying agent in brewing, and for paper sizing fabrics. Laxatives (or purgatives) are foods, compounds, or drugs taken to induce bowel movements or to loosen the stool, most often taken to treat constipation. ... For animals adapted to eat primarily plants, sometimes referred to as vegetarian animals, see Herbivore. ... For the art collective, see Gelitin. ... Jam from berries Fruit preserves refers to fruit, or vegetables, that have been prepared and canned for long term storage. ... Missing image Ice cream is often served on a stick Boxes of ice cream are often found in stores in a display freezer. ... Anmitsu (あんみつ) is a traditional Japanese dessert popular for many centuries. ... A 16th century brewer A 21st century brewer This article concerns the production of alcoholic beverages. ... This article or section does not cite any references or sources. ...

Chemically, agar is a polymer made up of subunits of the sugar galactose. Agar polysaccharides serve as the primary structural support for the algae's cell walls. A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... Galactose (also called brain sugar) is a type of sugar found in dairy products, in sugar beets and other gums and mucilages. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ...

Names

The word "agar" comes from the Malay word agar-agar (meaning jelly). It is also known as kanten, China grass, or Japanese isinglass. The various species of alga or seaweed from which agar is derived are sometimes called Ceylon moss. Gracilaria lichenoides specifically is referred to as agal-agal or Ceylon agar.^[1] Not to be confused with the Malayalam language, spoken in India. ...

In Malay and Indonesian, it is known as agar-agar. In Japanese, it is known as kanten (寒天) meaning "cold weather," referring to the fact that it is harvested in the winter months. In Mandarin Chinese as yángcài (洋菜) meaning "ocean vegetable" or "foreign vegetable." In Taiwanese Minnan it is known as chhài-iàn (菜燕) meaning "vegetable swiftlet," i.e., similar in texture to the nest of the edible-nest swiftlet used in bird's nest soup. In China, it is known as 海藻瓊脂 or 凍粉. In the Philippines, it is known as gulaman in Tagalog, Apayao, Bikol, and Pangasinan, guraman in Ilokano and gurguraman in Sambali.^[2] In Thai it is known as wóon (วุ้น). Map of eastern China and Taiwan, showing the historic distribution of Mandarin Chinese in light brown. ... For other uses, see Formosan languages, Taiwanese Mandarin, and Languages of Taiwan. ... Mǐn Nán (Chinese: 閩南語), also spelt as Minnan or Min-nan; native name Bân-lâm-gú; literally means Southern Min or Southern Fujian and refers to the local language/dialect of southern Fujian province, China. ... Genera Hydrochous Collocalia Aerodramus Schoutedenapus Bold text The birds called Swiftlets or Cave Swiftlets are contained within the four genera Aerodramus, Hydrochous, Schoutedenapus and Collocalia. ... Genera Hydrochous Collocalia Aerodramus Schoutedenapus The birds called Swiftlets or Cave Swiftlets are contained within the four genera of Aerodramus, Hydrochous, Schoutedenapus and the remaining species left in Collocalia. ... The key ingredient of bird-nest soup Bird Nests box showing $888. ... Tagalog (pronunciation: ) is one of the major languages of the Republic of the Philippines. ... Bicolano or Bikol is an Austronesian language used in the Philippines particularly on the Bicol Peninsula on the island of Luzon. ... The Pangasinan language (Pangasinan: salitan Pangasinan; Spanish: idioma pangasinense) belongs to the Malayo-Polynesian languages branch of the Austronesian languages family. ... To view the Ilokano edition of this Wikipedia article, select from the in other languages Ilokano (variants: Ilocano, Iluko, Iloco, and Iloko) is the third most-spoken language of the Republic of the Philippines. ... Sambal (Spanish: zambal) is a Sambalic language spoken primarily in the province of Zambales in the Philippines. ...

Usage

Microbiology

Culture Medium

Main article: Agar plate

Nutrient agar is used throughout the world to provide a solid surface containing medium for the growth of bacteria and fungi. Though less than 70% of all existing bacteria can be grown successfully, the basic agar formula can be used to grow most of the microbes whose needs are known. More specific nutrient agars are available, because some microbes prefer certain environmental conditions over others. An agar plate streaked with microorganisms isolated from a deep-water sponge. ... An Agar Plate -- an example of a bacterial growth medium. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ...

Motility assays

As a gel, an agarose medium is porous and therefore can be used to measure microorganism motility and mobility. The gel's porosity is directly related to the concentration of agarose in the medium, so various levels of effective viscosity (from the cell's "point of view") can be selected, depending on the experimental objectives.

A common identification assay involves culturing a sample of the organism deep within a block of nutrient agar. Cells will attempt to grow within the gel structure. Motile species will be able to migrate, albeit slowly, throughout the gel and infiltration rates can then be visualized; whereas non-motile species will only show growth along then now-empty path introduced by the invasive initial sample deposition.

Another setup commonly used for measuring chemotaxis and chemokinesis utilizes the under-agarose cell migration assay whereby a layer of agarose gel is placed between a cell population and a chemoattractant. As a concentration gradient develops from the diffusion of the chemoattractant into the gel, various cell populations requiring different stimulation levels to migrate can then be visualized over time using microphotography as they tunnel upward through the gel against gravity along the gradient.

Molecular biology

Agar is a heterogeneous mixture of two classes of polysaccharide: agaropectin and agarose.^[3] Although both polysaccharide classes share the same galactose-based backbone, agaropectin is heavily modified with acidic side-groups, such as sulfate and pyruvate. The neutral charge and lower degree of chemical complexity of agarose make it less likely to interact with biomolecules, such as proteins. Gels made from purified agarose have a relatively large pore size, making them useful for size-separation of large molecules, such as proteins or protein complexes >200 kilodaltons, or DNA fragments >100 basepairs. Agarose can be used for electrophoretic separation in agarose gel electrophoresis or for column-based gel filtration chromatography. For specific types of electrophoresis (for example, the process of administering medicine, iontophoresis), see electrophoresis (disambiguation). ... Digital image of 3 plasmid restriction digests run on a 1% w/v agarose gel, 3 Volts/cm, stained with ethidium bromide. ... Equipment for running size exclusion chromatography. ...

Plant biology

Research grade agar is used extensively in plant biology as it is supplemented with a nutrient and vitamin mixture that allows for seedling germination in petri dishes under sterile conditions (given that the seeds are sterilized as well). Nutrient and vitamin supplementation for Arabidopsis thaliana is standard across most experimental conditions. Murashige & Skoog (MS) nutrient mix and Gamborg's B5 vitamin mix are generally used. A 1.0% agar/0.44% MS+vitamin dH20 solution is suitable for growth media between normal growth temps. This article or section does not cite its references or sources. ...

The solidification of the agar within any growth media (GM) is pH-dependent, with an optimal range between 5.4-5.7. Usually, the application of KOH is needed to increase the pH to this range. A general guideline is about 600 µl 0.1M KOH per 250 ml GM. This entire mixture can be sterilized using the liquid cycle of an autoclave. Front loading autoclaves are common Stovetop autoclaves need to be monitored carefully and are the simplest of all autoclaves Multiple large autoclaves are used for processing substantial quantities of laboratory equipment prior to reuse, and infectious material prior to disposal. ...

This medium nicely lends itself to the application of specific concentrations of phytohormones etc. to induce specific growth patterns in that you can easily prepare a solution containing the desired amount of hormone, add it to the known volume of GM and autoclave to both sterilize and evaporate off any solvent you may have used to dissolve the often polar hormones in. This hormone/GM solution can be spread across the surface of petri dishes sown with germinated and/or etiolated seedlings.

Culinary

Agar-Agar is a natural vegetarian gelatin counterpart originally eaten in Japan. White and semi-translucent, it is sold in packages as washed and dried strips or in powdered form. It can be used to make jellies, puddings and custards. For making jelly, it is boiled in water until the solids dissolve. One then adds sweetener, flavouring, colouring, fruit or vegetables, and pours the liquid into molds to be served as desserts and vegetable aspics, or incorporated with other desserts, such as a jelly layer on a cake. For the art collective, see Gelitin. ... One half of a bronze mold for casting a socketed spear head dated to the period 1400-1000 BC. There are no known parallels for this mold. ... ASPIC can refer to: Advanced SCSI Programmable Interrupt Controller Application Service Provider Industry Consortium Armed Services Personnel Interrogation Center Association for Strategic Planning in Internal Communications Authors Standard Prepress Interfacing Cod This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same... For other uses, see Cake (disambiguation). ...

Agar-agar is approximately 80% fiber, so it can serve as a great intestinal regulator. Its bulk quality is behind one of the latest fad diets in Asia, the kanten diet. Once ingested, kanten triples in size and absorbs water. This results in the consumer feeling more full. Recently this diet has received some press coverage in the United States as well. The diet has shown promise in obesity studies.^{[citation needed]}

One use of agar in Japanese cuisine is anmitsu, a dessert made of small cubes of agar jelly and served in a bowl with various fruits or other ingredients. In Indian cuisine, agar agar is known as "China grass" and is used for making desserts. In Burmese cuisine, a sweet jelly known as kyauk kyaw (​ေကျာက်​ေကြာ [tʃaoʔtʃau]) is made from agar. There are many views as to what defines Japanese cuisine, as the everyday food of the Japanese people has diversified immensely over the past century or so. ... Anmitsu (あんみつ) is a traditional Japanese dessert popular for many centuries. ... Not to be confused with Native American cuisine. ...

Other

Agar is used as an impression material in dentistry. It is also used to make salt bridges for use in electrochemistry. In terms of dentistry an impression may be described as an accurate representation of a persons dentition. ... This article is about the dental profession. ... English chemists John Daniell (left) and Michael Faraday (right), both credited to be founders of electrochemistry as known today. ...

Agar is used in formicariums as a transparent substitute for sand and a source of nutrition. Ants tunneling through an Ant Farm The Ant Farm is essentially a colony of ants enclosed between two panes of glass. ...

Hysteresis

Hysteresis describes the phenomenon of the differing liquid-solid state transition temperatures that agar exhibits. Agar melts at 85 °C (358 K, 185 °F) and solidifies from 32-40 °C. (305 - 313 K, 90-104 °F) A system with hysteresis can be summarised as a system that may be in any number of states, independent of the inputs to the system. ... The dissociation of a double-stranded DNA molecule is often referred to as melting because it occurs quickly once a certain temperature has been reached. ...

See also

• Carrageenan
• Rhodophyta
• Asepsis
• Agarose gel electrophoresis
• Petri dish
• Robert Koch
• Walter Hesse
• R2a agar

Carrageenans or carrageenins (pronounced ) are a family of linear sulphated polysaccharides extracted from red seaweeds. ... Red algae Classes Florideophyceae Bangiophyceae Cyanidiophyceae The red algae are a large group of mostly multicellular, marine algae, including many notable seaweeds. ... Asepsis is the practice to reduce or eliminate contaminants (such as bacteria, viruses, fungi, and parasites) from entering the operative field in surgery or medicine to prevent infection. ... Digital image of 3 plasmid restriction digests run on a 1% w/v agarose gel, 3 Volts/cm, stained with ethidium bromide. ... Man looking at fungus inside of petri dishes A Petri dish is a shallow glass or plastic cylindrical dish that biologists use to culture microbes. ... For the American lobbyist, see Bobby Koch. ... Walter Hesse is best known for his work in microbiology, specifically his work in developing Agar as a medium for culturing microorganisms. ...

References