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. Gelatin (also gelatine, from French gélatine) is a translucent colourless brittle nearly tasteless solid substance, extracted from the In Biology a substrate is the surface a plant or animal lives upon A growth medium or culture medium is a liquid or gel designed to support the growth of Microorganisms or cells There are different types of media for Microbiology (from Greek grc μῑκρος mīkros, "small" grc βίος bios, " Life " and grc -λογία 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). Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer The red algae (Rhodophyta ˌroʊdəˈfaɪtə roʊˈdɒfɨtə from Greek: ῥόδον (rhodon = rose + φυτόν (phyton = plant thus red plant are A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic Gelidium is a small Genus of Red algae containing 114 species 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 Seaweed is a loose colloquial term encompassing macroscopic Multicellular, benthic marine Algae. Commercially it is derived primarily from Gelidium amansii. Gelidium amansii is an economically important species of Red algae commonly found in the shallow coast of many East and Southeast Asian countries

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. Vegetarianism is the practice of a diet that excludes Meat (including game and slaughter by-products Fish (including Shellfish and other sea Gelatin (also gelatine, from French gélatine) is a translucent colourless brittle nearly tasteless solid substance, extracted from the Ice cream or ice-cream (originally iced cream) is a frozen dessert made from Dairy products such as Milk and Cream, combined For a topic outline on this subject see List of basic Japan topics. is a Japanese Dessert that has been popular for many decades It is made of small cubes of Agar jelly a white translucent jelly made from Red algae or Brewing is the production of Alcoholic beverage and Alcohol fuel through fermentation. Sizing or size is a Substance that is applied to Porous materials as a Glaze or Filler.

Chemically, agar is a polymer made up of subunits of the sugar galactose. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Galactose (Gal (also called brain sugar) is a type of Sugar which is less sweet than Glucose. Agar polysaccharides serve as the primary structural support for the algae's cell walls. Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds

Names

The word "agar" comes from the Malay word agar-agar (meaning jelly). The Malay language ( ISO 639-1 code MS is an Austronesian language spoken by the Malay people and people of other ethnic groups who reside in the 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]

In Malay and Indonesian, it is known as agar-agar. Indonesian or Bahasa Indonesia, based on the Riau version of Malay language, was declared the official language with the declaration of 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. Standard Mandarin, also known as Standard Spoken Chinese, is the official modern Chinese spoken language used in mainland China and Taiwan " In Taiwanese Minnan it is known as chhài-iàn (菜燕) meaning "vegetable swiftlet," i. The Southern Min language or Min Nan ( POJ: Bân-lâm-gú or "Southern Fujian" language refers to a family of Chinese languages Dialects Swiftlets or cave swiftlets are Birds contained within the four genera Aerodramus, Hydrochous, Schoutedenapus and e. , similar in texture to the nest of the edible-nest swiftlet used in bird's nest soup. The Edible-nest Swiftlet ( Aerodramus fuciphagus) is a small Bird of the Swift family which is found in South-east Asia. Bird's nest soup is a delicacy in Chinese cuisine. A few species of swift, the cave swifts, are renowned for building the saliva nests used to In Korea, it is known as 한천. Korea is a geographic area composed of two sovereign countries a civilization and a former state situated on the Korean Peninsula in East Asia. In China, it is known as 海藻瓊脂 or 凍粉. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National In the Philippines, it is known as gulaman in Tagalog, Apayao, Bikol, and Pangasinan, guraman in Ilokano and gurguraman in Sambali. The Philippines ( Filipino: Pilipinas, officially known as the Republic of the Philippines (fil ''Republika ng Pilipinas'' RP Tagalog is one of the major languages used in the Philippines. For the macrolanguage Bikol see Bikol languages. Bikol refers to Central Bicolano (also known as Bikol Central The Pangasinan language (Pangasinan salitan Pangasinan; Spanish: idioma pangasinense, sometimes called Panggalatok belongs to the Malayo-Polynesian To view the Ilokano edition of this Wikipedia article select from the in other languages section to the side of this page The Sambalic languages are part of the Central Luzon language family ^[2] In Thai it is known as wóon (วุ้น). Thai (th ภาษาไทย, transcription: phasa thai, transliteration:; pʰāːsǎːtʰāj is the national and

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. An agar plate is a sterile Petri dish that contains a Growth medium (typically Agar plus nutrients used to culture Microorganisms A growth medium or culture medium is a liquid or gel designed to support the growth of Microorganisms or cells There are different types of media for The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ 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. A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually More specific nutrient agars are available, because some microbes prefer certain environmental conditions over others.

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. Electrophoresis is the most well-known electrokinetic phenomenon. Agarose Gel electrophoresis is a method used in Biochemistry and Molecular biology to separate DNA, or RNA molecules by size Size exclusion chromatography (SEC is a chromatographic method in which particles are separated based on their size or in more technical terms their Hydrodynamic volume

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. Murashige and Skoog medium or ( MSO or MS0 (MS-zero) is a Plant Growth medium used in the laboratories for A 1. 0% agar/0. 44% MS+vitamin dH20 solution is suitable for growth media between normal growth temps.

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. An autoclave is a pressurized device designed to heat aqueous solutions above their Boiling point at normal atmospheric pressure to achieve sterilization

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 vegetable gelatin counterpart originally eaten in Japan. Gelatin (also gelatine, from French gélatine) is a translucent colourless brittle nearly tasteless solid substance, extracted from the 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. Molding is the process of Manufacturing by shaping pliable raw material using a rigid frame or model called a pattern. Aspic is a dish in which ingredients are set into a Gelatine made from a Meat stock or Consommé. Cake is a form of Food that is usually sweet and often baked.

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.

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. Japanese Cuisine has developed over the centuries as a result of many political and social changes is a Japanese Dessert that has been popular for many decades It is made of small cubes of Agar jelly a white translucent jelly made from Red algae or 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. The cuisine of Myanmar (or Burma has been influenced by the respective cuisines of China, India and Thailand.

Other

Agar is used as an impression material in dentistry. A dental impression may be described as an accurate representation of part or all of a person's Dentition and other areas of the mouth Dentistry' is the "evaluation diagnosis prevention and/or treatment (nonsurgical surgical or related procedures of diseases disorders and/or conditions of the oral cavity It is also used to make salt bridges for use in electrochemistry. Electrochemistry is a branch of Chemistry that studies Chemical reactions which take place in a Solution at the interface of an electron conductor

Agar is used in formicariums as a transparent substitute for sand and a source of nutrition.

Hysteresis

Hysteresis describes the phenomenon of the differing liquid-solid state transition temperatures that agar exhibits. 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 Agar melts at 85 °C (358 K, 185 °F) and solidifies from 32-40 °C. (305 - 313 K, 90-104 °F)

See also

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

References