Agar solutions

Agar-agar solution Agaricus bisporus Agaritine [2757-90-6]... 

To clear slant tubes, culture agar solution is prepared. To have clear agar solution, it has to boil. Agar is a polysaccharide. It is not soluble in cold water, so heating helps to dissolve it in water. Once the solution is dispensed in the tube, it goes for sterilisation. Agar is in the solid state at room temperature, about 35 °C. 

Bottom layer Melt the 1% agar solution in boiling water or in a microwave oven, and cool it to 40°C in a water bath set at that temperature. In the same water bath, warm the concentrated (2x) medium. Mix equal volumes of the two solutions to obtain 0.5% agar in 1 x culture medium, 1 x (e.g. 10%) PCS. Add enough volume to make a thick layer on the bottom of the well (typically, 1.0 ml/well is used for 24 multiwell plates, 1.5 ml/well is used for 6 multiwell plates), and let it set at room temperature until it is hardened. The plates can now be stored at 4°C for up to 1 week. 

After the S precipitate on the fluted funnel, prepared according to method I, has been washed, it is mixed with sufficient 10% agar solution and dilute NaOH to reach a concentration of 0.6% agar and 0.4% NaOH in the sol product, relative to the weight of dry svilfur. The mixture is then decanted from the insoluble components. The resulting sol is very stable. 

Agar was chosen as the support to be tested because of convenience and the mild conditions necessary for immobilization. A 3% agar solution at 40-50°C was mixed with a concentrated suspension of frozen-thawed cells held at 30-40 C. The suspension was poured into 1-ml aluminum cups and allowed to solidify. A cylinder of agar (12 mm dicuneter x 10 mm) was removed from each cup and used as the enzyme source. The enzyme activity of this immobilized preparation is shown in Figure 2 the requirement for ATP is easily seen. Such preparations have a half-life of atxjut 100 hours at 37°C when incubated in the presence of reaction mixture. About 1000 hours are necessary to inactivate such a preparation completely. 

It has already been stated that, in thermoreversible gels, the sol-gel transition temperature is no precisely defined constant and that it depends on the rate of cooling, and further that hysteresis phenomena occur. An 0.5% ar-agar solution sets to a gel when cooled to 35°. When heated, it liquefies again, but not until a temperature of 90° is reached. Below 90° the gel does not liquefy, however long it may be maintained at the particular temperature. Consequently, it is possible to obtain this system either in a sol or a gel condition at any temperature between 35° and 90°. This is an extreme case, but most of the thermoreversible sol-gel transformations show hysteresis to such a degree, that the sol or the gel state can be obtained within a temperature of 10 to 20 degrees. ... 

The following table shows the yield point of dilute agar-agar solutions as measured by Michaud ... 

VIELD VALUE OF AGAR-AGAR SOLUTIONS MEASURED BY MICHAUD... 

When the agar has cooled down, add the albumen to the agar solution and swirl gently to mix add 2.4ml of the lOOx antibiotic-antimycotic stock while continuing to mix. Using a sterile 10 ml pipet and pipet aid, distribute 2.5 ml agar-albumen into each petri dish, avoiding the formation of bubbles. Do not dispense more than 2.5 ml, since a thicker substrate will make observation of the embryos more difficult. 

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