As a gel, an agar or 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. Yadav, Lokenddra; Thomas, Sarega; Kini, Usha (February 2015). "Improvised double-embedding technique of minute biopsies: A mega boon to histopathology laboratory". Indian Journal of Pathology and Microbiology. 58 (1): 12–6. doi: 10.4103/0377-4929.151156. PMID 25673584. Balfour, Edward. (1885). The cyclopædia of India and of eastern and southern Asia: commercial, industrial and scientific, products of the mineral, vegetable, and animal kingdoms, useful arts and manufactures. B. Quaritch. p. 71. Kim, Se-Kwon (2011). Handbook of marine macroalgae: biotechnology and applied phycology (1st imp.ed.). Hoboken, NJ: John Wiley & Sons Inc. ISBN 9780470979181. LB agar". Cold Spring Harbor Protocols. 2009 (3): pdb.rec11683. 2009-03-01. doi: 10.1101/pdb.rec11683. ISSN 1940-3402.

Clark, David P.; Pazdernik, Nanette J.; McGehee, Michelle R. (2019-01-01), Clark, David P.; Pazdernik, Nanette J.; McGehee, Michelle R. (eds.), "Chapter 7 - Cloning Genes for Synthetic Biology", Molecular Biology (Third Edition), Academic Cell, pp.199–239, doi: 10.1016/b978-0-12-813288-3.00007-0, ISBN 978-0-12-813288-3, S2CID 91889487 , retrieved 2022-12-12Different algae produce various types of agar. Each agar has unique properties that suit different purposes. Because of the agarose component, the agar solidifies. When heated, agarose has the potential to melt and then solidify. Because of this property, they are referred to as "physical gels." In contrast, polyacrylamide polymerization is an irreversible process, and the resulting products are known as chemical gels. Warm up the liquid as much as possible. One advantage of agar agar is that it begins to set at a higher temperature than gelatin, so it is a solid at room temperature or even when you warm it up. The liquid will begin to gel when it falls below 113 °F (45 °C). Because the addition of other ingredients may cause the temperature to drop and the agar agar to set before you are ready, getting the liquid as hot as you can will make it less likely to drop below 113 °F (45 °C) until you remove it from heat.

Agar". London South Bank University. Archived from the original on 2022-09-26 . Retrieved 2023-03-21. 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 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. Nutrients are typically added to meet the nutritional needs of the microbes organism, the formulations of which may be "undefined" where the precise composition is unknown, or "defined" where the exact chemical composition is known. Agar is often dispensed using a sterile media dispenser.Agar ( / ˈ eɪ ɡ ɑːr/ or / ˈ ɑː ɡ ər/), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from "ogonori" ( Gracilaria) and "tengusa" ( Gelidiaceae). [1] [2] As found in nature, agar is a mixture of two components, the linear polysaccharide agarose and a heterogeneous mixture of smaller molecules called agaropectin. [3] It forms the supporting structure in the cell walls of certain species of algae and is released on boiling. These algae are known as agarophytes, belonging to the Rhodophyta (red algae) phylum. [4] [5] The processing of food-grade agar removes the agaropectin, and the commercial product is essentially pure agarose. 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 and 5.7. [42] Usually, the application of potassium hydroxide 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. Birgit Hadeler; Sirkka Scholz; Ralf Reski (1995). "Gelrite and agar differently influence cytokinin-sensitivity of a moss". Journal of Plant Physiology. 146 (3): 369–371. doi: 10.1016/s0176-1617(11)82071-7. Agar agar is a plant-based gelling agent derived from seaweed, commonly used in cooking and food production.

McIlvain, Grace; Ganji, Elahe; Cooper, Catherine; Killian, Megan L.; Ogunnaike, Babatunde A.; Johnson, Curtis L. (September 2019). "Reliable preparation of agarose phantoms for use in quantitative magnetic resonance elastography". Journal of the Mechanical Behavior of Biomedical Materials. 97: 65–73. doi: 10.1016/j.jmbbm.2019.05.001. PMC 6699912. PMID 31100487.Manufacturers boil the seaweed to extract the agar agar. Then, they dry it and form it into bars, strands, powder, or flakes for commercial use. Agar consists of a mixture of two polysaccharides: agarose and agaropectin, with agarose making up about 70% of the mixture, while agaropectin makes about 30% of it. [25] 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. [26] 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, glucuronate, and pyruvate. [27] [25] [26] Physical properties [ edit ] Let cool 20 to 40 minutes in the refrigerator, until slightly firm. To serve, gently slide a small knife around the edge of the flan, then flip flan onto individual serving plates. Sprinkle lemon zest on top for garnish, if desired.