beef paste protein culture-base is one of the most widely used and common bacterial foundations ef, sometimes referred to as a common media. It contains beef paste, and NaCl. Among them, beef paste provides carbon sources and energy sources for microorganisms, phosphates, proteins mainly provide nitrogen sources, and NaCl provides inorganic salts. In the preparation of solid media, a certain amount of < a href"" > agar be added as a coagulant. Agar melts at a common concentration of 96 degrees C, generally in the boiling water bath or under the pad boiling melt in asbestos mesh, so as not to burn agar. Agar solidifies at 40 degrees C and is usually not used by microbial decomposition. The content of agar in solid mediums varies depending on the quality and temperature of agar.
Because this medium is mostly used to culture bacteria, it is suitable for the growth and reproduction of bacteria by using thin acid or alkali to neutral or slightly alkaline.
beef paste protein the formulation of the culture base is as follows:
pH 7． 4—7． 6
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beef paste, protein, NaCl, agar;
1mol/L NaOH, 1mol/L HCl;
test tube, triangular burner, beaver, tube, stick, Medium displodator, torque balance, horn spoon, high-pressure steam sterilization pot, pH "test paper (pH 5. 5—9． 0), cotton, cow paper, marker pen, hemp rope, gauze, etc.
II, beef paste protein the production steps of the culture
accurately named beef paste, protein and NaCl in the beech in proportion to the medium formula. Beef paste is often picked with a stick, weighed in a small beech or surface dish, dissolved with hot water and poured into a berries. Can also be placed on the weighing paper, weighing directly into the water, such as a slightly heating, the beef paste will be separated from the weighing paper, and then immediately remove the pieces of paper. Protein easy to absorb moisture, in the call to move quickly. In addition, when the drug is strictly prevented from mixing, a cow's horn spoon is used for a drug, or take a drug, wash, dry, and then take another drug, bottle cap also do not cover the wrong.
in the above berries can be added less than the required amount of water, stirred with a glass stick, and then heated on the asbestos network to dissolve. After the drug is completely dissolved, rehydrate to the desired total volume. If a solid medium is prepared, put the well-known agar into the melted medicine, reheat the melting, in the process of agar melting, need to constantly stir, in order to prevent agar paste bottom to break the beech. Finally, make up for the lost water.
3． Tune pH
measure the original pH of the medium with precision pH test paper before tuning pH, and if pH is acidic, add 1mol/L NaOH to the medium with a dropper, stir side by side, and measure the pH of the medium at any time, until Hp7. 6。 Conversely, 1mol/L HCl is used to adjust. Note that the pH should not be turned over to avoid a callback, otherwise the concentration of ions in the media will be affected.
For some microorganisms that require a more accurate pH, the adjustment of their pH can be made using an acid meter (use method, refer to the relevant instructions).
4． < a href" > filter
filtered with filter paper or multi-layer gauze while hot for observation of the results. In general, this step can be eliminated without special requirements (no filtering is required for this experiment).
the preparation of the culture base can be packed into a test tube or triangular cans, as required by the experiment. The disloading device is shown in Figure V.-1.
parting process care not to put the culture on the tube or bottle mouth, so as not to stain the cotton plug and cause contamination.
(1) liquid packing height is appropriate at about 1/4 of the test tube height.
(2) solid sub-pack test tube, which does not exceed 1/5 of the pipe height, sterilized into a slope, as shown in figure V.-2. The amount of triangular cans shall not exceed half of the volume of the triangular cans.
(3) semi-solid sub-pack test tube is generally suitable for test tube height of 1/3, vertical after sterilization to be condensed.
culture base is packed, cotton plugs are inserted on the test tube port or triangular burner port to prevent outside microorganisms from entering the culture base, resulting in contamination and good breathability (after the cotton plug production method is attached to this experiment).
after the plug, all test tubes are tied with hemp rope, and then outsource a layer of psoriate paper in cotton plugs to prevent sterilization when condensed water moistening cotton plugs, and then with a hemp rope outside. Indicate the name, group, and date of the culture base with a marker pen. After the triangular flanter is stuffed, outsourced verse paper, with hemp rope in the form of live knots, easy to unwrap when used, the same marker pen to indicate the name of the culture base, group, date.
the above-mentioned culture base to 1. 05kg/cm2 (15lbs/inch 2), 121. 3 degrees C, 20 minutes of high-pressure steam sterilization. If sterilization is not caused by special circumstances, it should be put in the refrigerator for staging.
9． Shelve the slope
cools the sterilized test tube culture to about 50 degrees C, places the test tube plug end on the stick, and the slope length of the shelving is appropriate not more than half the length of the test tube.
10． Sterile check
put the sterilized medium in a greenhouse at 37 degrees C and cultured it for 24-48 hours to check that the sterilization is thorough.