agar

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agar

(ä`gär, ā`–, ăg`är), product obtained from several species of red algae, or seaweedseaweed,
name commonly used for the multicellular marine algae. Simpler forms, consisting of one cell (e.g., the diatom) or of a few cells, are not generally called seaweeds; these tiny plants help to make up plankton.
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, chiefly from the Ceylon, or Jaffna, moss (Gracilaria lichenoides) and species of Gelidium, harvested in eastern Asia and California. Chemically, agar is a polymer made up of subunits of the sugar galactose; it is a component of the algae's cell walls. Dissolved in boiling water and cooled, agar becomes gelatinous; its chief uses are as a culture medium (particularly for bacteria) and as a laxative, but it serves also as a thickening for soups and sauces, in jellies and ice cream, in cosmetics, for clarifying beverages, and for sizing fabrics. See also RhodophytaRhodophyta
, phylum (division) of the kingdom Protista consisting of the photosynthetic organisms commonly known as red algae. Most of the world's seaweeds belong to this group.
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Agar

(ā`gər), the same as HagarHagar
or Agar
, according to the Book of Genesis, servant of Abraham's wife Sarah and mother of his eldest son, Ishmael. She and her son were sent out into the wilderness because of Sarah's jealousy. An angel aided her there.
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Agar

A major constituent of the cell walls of certain red algae, especially members of the families Gelidiaceae and Gracilariaceae. Extracted for its gelling properties, it is one of three algal polysaccharides of major economic importance, the others being alginate and carrageenan. Agar is composed of two similar fractions, agarose and agaropectin, in which the basic unit is galactose, linked alternately α-1,3-( d -galactose) and β-1,4-(α- l -galactose).

Agar is prepared by boiling the algae in water, after which the filtered solution is cooled, purified, and dried. It is an amorphous, translucent material that is packaged in granules, flakes, bricks, or sheets. One of its chief uses is as a gelling agent in media for culturing microorganisms. It is also used in making confections, as an emulsifier in cosmetics and food products, as a sizing agent, as an inert carrier of drugs in medicine, and as a laxative. See Culture

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.

agar

[′äg·ər]
(materials)
A gelatinous product extracted from certain red algae and used chiefly as a gelling agent in culture media.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

agar

a complex gelatinous carbohydrate obtained from seaweeds, esp those of the genus Gelidium, used as a culture medium for bacteria, a laxative, in food such as ice cream as a thickening agent (E406), etc.
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
TABLE 2: Results of the agar diffusion test. The plus signs indicate the presence of a zone of inhibition around a piece of quat-modified PE that was placed on a carpet of bacteria cultured on agar.
The results of the agar diffusion test showed that all 3 sealers exhibited antibacterial activity against A.
However, in the direct agar diffusion test, the "L" and "3L" groups showed moderate cytotoxicity (Figure 3), with a cell lysis zone extending from the specimen up to 1 cm.
Antibacterial Agar Diffusion Test. To perform the antibacterial agar diffusion test of GNR-grafted Ti[O.sub.2] nanotubes, Streptococcus mutans (ATCC 25176, ATCC, USA) was incubated in brain-heart infusion broth (BHIB; Difco Co., USA).
The commonly used temperature with Agar Diffusion Test is 37degC.
MICs were determined by using the agar diffusion test, according to Clinical and Laboratory Standards Institute recommendations (7).
aureus strains develop a resistance against commonly used antibiotics, agar diffusion tests were carried out to check for cross resistance.