With its characteristic smell, you can easily distinguish
agar with other materials, usually found in the laboratory. Chemically, agar is a polymer consisting of units of sugar galactose, and is a component of cell walls of certain red algae, which are usually collected in Asia and California. Dissolved in boiling water, cooled, laboratory agar looks gelatinous. Although the main use of agar is a nutrient medium for various microorganisms, especially bacteria, its other, lesser-known areas of application include is thickening for soups and sauces, in jellies, ice cream, in cosmetics, for clarifying beverages, and for determination of tissue. (1) One could ask why the agar, unlike regular gelatin (as found in the jelly) is used for culturing bacteria. A agar, unlike gelatin, while not worsening (eat) bacteria. In addition, agar harder and stronger than gelatin. It is still possible, however, use gelatin as a nutrient medium for bacteria if agar is not available. (2) Difco BBL Manual gives more details on the agar and its use: (3) Agar is phycocolloid extracted from a group of red-purple marine algae (Class Rhodophyceae), including Gelidium,
Pterocladia and Gracilaria. Gelidium is the best source of agar. Impurities, debris, minerals and pigments are reduced to these levels in the production process. Agar is a gel strattera dosage at room temperature, the other firms at a temperature higher than 65C. Agar melts at approximately 85S, a different temperature from that at which it solidifies, 32-40C. This property is called hysteresis. Agar is generally resistant to lateral forces, however, different agar may have different strengths and gel firmness. Agar is commonly used in the final concentration of 1-2% for the promotion of culture media. Small amounts (0. 05-0. 5%) is used in media for motility studies (0. 5% weight / volume) and for the growth of anaerobes (0. 1%) and microaerophiles. Specifications for bacteriological grade agar include good transparency, temperature control heleobrazovanyya controlled by melting point, good features of diffusion, the lack of toxic bacterial inhibitors and the relative lack of metabolically useful minerals and compounds. For students, growing bacteria at home unattended teacher (for example, the study of bacteria in different places around the house), it is important to use agar formulations that do not grow mostly one type of bacteria over others. In the worst case is the one that mainly grew pathogenic bacteria. Therefore, we recommend a simple >> << nutrient agar, with yaks
LB agar is a subtype. There are many different suppliers for the LB agar. Because some vendors will not sell directly to students, you can have your teacher for you. If you do a project that involves grafting and plate lines, we strongly recommend an experiment in the school laboratory under the supervision of a teacher. (5) Preliminary experiment: Keep sterile Petri dishes closed until ready to pour them in agar. Airborne pollution by easily invade an open Petri dish. Although pre-poured agar available, you can make agar tablets, powder or bottled agar by following some simple instructions. Agar kits usually come with detailed instructions on how to prepare the plate, and below are examples of procedures for reference. If in doubt, do not forget to clearly read the manual and ask for help if necessary (or contact the teacher or call the service provider of technical assistance package agar). The wording of LB (Luria Bertani) agar: 9. 1 g / l trypton, 4. 6 g / l yeast extract, 4. 6 g / l NaCl, and 13. 7 g / l agar. Using tablets, 10 tablets dissolved in 500 ml of water. For agar powder dissolved in a microwave oven, 6. 9 g agar in 500 ml of water. 500 ml of agar poured ~ 25 large Petri dish (diameter 100 mm) or 50 small Petri dishes (diameter 60 mm). Loosen the cap of the bottle, but do not remove cover during heating. Warm agar bottle in a bath of hot water or in microwave until it becomes liquid. After opening the lid, transfer the bottle neck agar over a flame to sterilize. Do not miss the cover! While pouring agar, open Petri dish as small as possible, keep it at an angle, and make sure the lid is held directly on the Petri dish. Pour enough melted agar into each sterile plastic Petri dish to cover 1/8 "bottom. Close the Petri dish immediately. Plates Place on the desktop agar to cool and set. Agar medium will set as hard gelatin at room. temperature Submit neck agar bottle through flame again before applying the cap Preparing Pre Lily plate. If the plates were frozen install them and allow them to warm to room temperature storage. agar plates stack upside down in the refrigerator. Do not freeze! to accommodate plates up down to prevent condensation drops down to the surface of agar which then would facilitate the movement of organisms between colonies. Please contact for further help. (6) While stirring soup decision, you should pay particular attention to the beginning of the movement scale to low and add more speed from there. When heated soup, make sure to cover the bulb so it can not be boiling, but to avoid leakage. When pouring broth, be sure to fill the Petri dish without burning yourself. Also important in this process, make sure that Petri dish is covered immediately solve the substance to cool proportionately. After Petrie were exposed or vaccinated, students should not re-open them. (7) Place the petri dish in each bag zip lock to prevent drying and to control odors. Turn the plate upside down and put them in a warm place. For many microorganisms, ideal temperature for incubation of 32C or 90F. Bacterial growth should start to become visible within 2-3 days. For those bacteria that grow in the home (eg, studies of bacteria in different places around the house), you can use homemade "light bulb incubator." on-site laboratory incubator This page describes how to build a "light incubator"
(8) After the Petri dishes were covered with tape, they should not be opened again all microorganisms are grown in. The experiment must be killed to write-off. The best way to get rid of bacterial cultures is to pressure them to sterilize heat stable biological bag. If autoclaves and pressure cookers are not available or large enough to make it comfortable alternative to bleaching plates. Saturate the plates with 20% "1 of 5" solution of household bleach (in other words, 1 part bleach and 4 parts water). Let them sit and soak overnight in a solution of bleach before disposing of them. Note that sodium hypochlorite is corrosive and should be completely removed after the addition, the plates can be burned, if burning is access to the Medical Dictionary Dorland in .. University of Texas Health Science Center at Houston: (1) "agar plate. "Wikipedia., Total as of January 14, 2005. (2), "Microbiology. "MadSci Network., On January 25, 2005. (3) "agar. "Difco BBL leadership., On January 17, 2008. (4) This is the catalog number on nutrient agar. Please follow the product description below, next number in the directory, not the picture caption, which deals with non-nutritive agar (5) "Hagar bottles -. use of training equipment. "Science stuff, Inc accessed January 14, 2005. (6), Motta and others. " Artificial medium for growing bacteria. "WW Bio Institute (www. Woodrow org/teachers/esi/2002/Biology/Projects/lab_skills/ls5 /.), Access to 14 January 2005 (7).». Agar bottle - use training equipment. "Science stuff, Inc accessed 14 January 2005 (8). Leung, Beatrice. Scientific consultant friends, e-mailing 10/01/05. Shijun Liu, Scientific Friends
Laurie Usinger, Bio-Rad Laboratories <<. >>
