Agar – wikipedia electricity for dummies amazon


Agar may have been discovered in Japan in 1658 by Mino Tarōzaemon ( 美濃 太郎 左衛門), an innkeeper in current Fushimi-ku, Kyoto who, according to legend, was said to have discarded surplus seaweed soup and noticed that it gelled later after a winter night’s freezing. [7] Over the following centuries, agar became a common gelling agent in several Southeast Asian cuisines. [8]

Beginning in the late 19th century, agar began to be used heavily as a solid medium for growing various microbes. Agar was first described for gas equations chemistry use in microbiology in 1882 by the German microbiologist Walther Hesse, an assistant working in Robert Koch’s laboratory, on the suggestion of his wife Fannie Hesse. [10] [11] Agar quickly supplanted gelatin as the base of microbiological media, due to its higher melting temperature, allowing microbes to be grown at higher temperatures without the media liquefying. [12]

With its newfound use in microbiology, agar production quickly increased. This production centered on Japan, which produced most of the world’s agar until World War II. [13] However, with the outbreak of World War II, many nations were forced to establish domestic agar industries in order to continue microbiological research. [13] Around the time of World War II, approximately 2,500 tons of agar electricity jeopardy powerpoint were produced annually. [13] By the mid-1970s, production worldwide had increased dramatically chapter 7 electricity and magnetism to approximately 10,000 tons each year. [13] Since then, production of agar has fluctuated due to unstable and sometimes over-utilized seaweed populations. [14] Etymology [ edit ]

The word agar comes from agar-agar, the Malay name for red algae ( Gigartina, Gracilaria) from which the jelly is produced. [15] It is also known as Kanten ( Japanese: 寒天) (from the phrase kan-zarashi tokoro ten ( 寒晒心太) or “cold-exposed agar”), Japanese isinglass, Ceylon moss or Jaffna moss. [16] Gracilaria lichenoides is specifically referred to as agal-agal or Ceylon agar. [17] Composition [ edit ]

Agar consists of a mixture of two polysaccharides: agarose and agaropectin, with agarose making up about 70% of the mixture. [18] Agarose is a linear polymer, made up of repeating units of agarobiose, a disaccharide made up of D-galactose and 3,6-anhydro-L-galactopyranose. [19] Agaropectin is a heterogeneous mixture of smaller molecules that occur in lesser amounts, and is made up of alternating units of D-galactose and L-galactose heavily modified with acidic side-groups, such as sulfate and pyruvate. [20] [18] [19]

Agar exhibits hysteresis, melting at 85 °C (358 K, 185 °F) and solidifying from 32–40 °C (305–313 K, 90–104 °F). [21] This electricity storage cost per kwh property lends a suitable balance between easy melting and good gel stability at relatively high temperatures. Since many scientific applications require incubation at temperatures close to human body temperature (37 °C), agar is more appropriate than other solidifying agents that melt at this temperature, such as gelatin.

Agar-agar is a natural vegetable gelatin counterpart. White and semi- translucent, it is sold in packages as washed and dried strips or in powdered gas stoichiometry form. It can be used to make jellies, puddings, and custards. For making jelly, it is boiled in water until the solids dissolve. Sweetener, flavouring, colouring, fruit or vegetables are then added and the liquid is poured into molds to be served as desserts and vegetable aspics, or incorporated with other desserts, such as a jelly layer in a cake.

Agar-agar is approximately 80% fiber, so it can serve as an intestinal regulator. Its bulking quality has been behind fad diets in Asia, for example the kanten (the Japanese word for agar-agar [4]) diet. Once ingested, kanten triples in size and absorbs water. This results in the consumers feeling fuller. This diet has recently received some press coverage in the United States as well. The diet has shown promise in obesity studies. [22]

In Russia, it is used in addition or as a replacement to pectin in jams and marmalades, as a substitute to gelatin for its superior gelling properties, and as a strengthening ingredient electricity test physics in souffles and custards. Another use of agar-agar is in ptich’ye moloko ( bird’s milk), a rich jellified custard (or soft meringue) used as a cake filling or chocolate-glazed as individual sweets. Agar-agar may also be used as the gelling agent in gel clarification, a culinary technique used to clarify stocks, sauces, and other liquids.

An agar plate or Petri dish is used to provide a growth medium using a mix of agar and other nutrients in which microorganisms, including bacteria and fungi, can be cultured and observed under the microscope. Agar is indigestible for many organisms so that microbial growth gas 85 vs 87 does not affect the gel used and it remains stable. Agar is typically sold commercially as a powder that can be mixed with water and prepared similarly to gelatin before use as a growth medium. Other ingredients are added to the agar to meet the nutritional needs of the microbes. Many specific formulations are available, because some microbes prefer certain environmental conditions over others. Agar is often dispensed using a sterile media dispenser.

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 gaz 67 sprzedam, albeit slowly, throughout the gel and infiltration rates can then be visualized, whereas non-motile species will show growth only along the 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 gas apple pay 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.

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 gas vs electric range 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 in general are used. A 1.0% agar/0.44% MS+vitamin dH 2O solution is suitable for growth media between normal growth temps.

When using agar, within any growth medium, it is important to know that the solidification of the agar is pH-dependent. The optimal range for solidification is between 5.4-5.7. [24] 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.

This medium nicely gas 4 less redding ca lends itself to the application of specific concentrations of phytohormones etc. to induce specific growth patterns in that one 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 that may have been used to dissolve the often-polar hormones. This hormone/GM solution can be spread across the surface of Petri dishes sown with germinated and/or etiolated seedlings.