1. Preparation of the solution: Add a part of a certain amount of water to the vessel, and according to the instructions, weigh the various raw materials required for the preparation of the medium, add them in order to dissolve, and finally make up the required water. For peptone, meat paste and other substances, it needs to be heated and dissolved, and the water evaporated by the heating process should be filled with water after all the raw materials are dissolved.
When preparing the solid medium, the above prepared liquid medium is boiled, and the weighed agar is added, and heating is continued until it is completely melted. Stir constantly to avoid burning the agar bottom.
2. Adjust pH
The pH of the medium is tested with a pH test strip (or pH potentiometer, hydrogen ion concentration colorimeter) and, if not required, can be adjusted with 10% HCl or 10% NaOH until the pH required for the formulation is adjusted.
3. Filter
The prepared medium is filtered with filter paper, gauze or cotton heat. When filtering with gauze, it is best to fold into six layers. When filtering with filter paper, the filter paper can be folded into a tile shape and spread on a funnel.
4. Packing
The filtered medium should be dispensed. If you want to make a slant medium, you must dispense the medium into a test tube. If a plate medium or a liquid, semi-solid medium is to be prepared, the medium must be dispensed into an Erlenmeyer flask.
When dispensing, hold the spring clip in one hand to allow the medium to flow out, and hold the test tube or conical flask in the other hand and pick up the medium in turn. When disassembling, be careful not to make the medium adhere to the nozzle or the bottle mouth to avoid contamination of the bacteria caused by soaking the cotton plug.
The amount of medium loaded into the test tube depends on the size of the test tube and the conical flask and the needs. Generally, when making a slant culture medium, each 15×150 mm test tube is filled with about 3 to 4 ml (1/4 to 1/3 of the test tube height). For example, a deep medium is prepared, and each tube of 20×220 mm is packed. 12 to 15 ml. The medium filled into each conical flask is generally half of its volume.
5. Add tampon
After the dispensing is completed, the tampon is required to block the nozzle or the mouth of the bottle. The main purpose of plugging tampon is to filter the air and avoid contamination. The tampon should be made of ordinary fresh and dry cotton. Do not use absorbent cotton to avoid the tampon being unusable due to the absorbent cotton. When making the tampon, spread the cotton to the appropriate thickness according to the size of the tampon, grab the size of the palm of your hand, place it in the round hole formed by the thumb and index finger of the left hand, insert the middle index finger into the middle of the cotton, and the index finger of the left hand and the thumb slightly. When gripped, a long stick-shaped tampon is formed. After the tampon is made, it should be quickly inserted into the nozzle or the mouth of the bottle. The tampon should be tightly attached to the inner wall without gaps to prevent the microbes in the air from invading along the wrinkles. Do not over-tighten the tampon. After plugging, it is suitable to use a portable cotton plug, tube or bottle. 2/3 of the tampon should be inside the tube or inside the bottle, and a little cotton is exposed at the upper end for easy extraction. Test tubes and conical flasks with tampon should be covered with thick paper and tied with rope to prepare for sterilization.
6. Making slant medium and plate medium
After the medium is sterilized, for example, a slant medium and a plate medium are prepared, and the sputum medium is not solidified.
(1) Making a slant medium. On the test bench, put a wooden strip with a length of about 0.5 to 1 meter and a thickness of about 1 cm. The head of the test tube is placed on the wooden strip, so that the medium in the tube is naturally inclined, and after solidification, it becomes a slant medium.
(2) Making a plate medium. Place the conical flask and culture dish containing the culture medium just off the experimental table, ignite the alcohol lamp, hold the bottom of the conical bottle bottle with your right hand, pull the cotton plug from the left hand, and slightly open the bottle mouth on the alcohol lamp. Add the burning, open the Petri dish cover with your left hand, and pour the culture medium into the Petri dish quickly with your right hand. Pour 10 ml into each dish to cover the bottom of the dish. After placing the medium, place it for about 15 minutes. After the medium is solidified, stack the 5 culture dishes, invert them, place them in an incubator, and check them after 24 hours. If the medium is long, the bacteria can be used. Culture microorganisms. And then freeze and store as described above. The advantage of this method is that it can be used to store cDNA libraries created on plasmid vectors.
Manual Juicer,Meat Hammer,Manual Meat Chopper,Paring Set,Tenderlizer
Shangwey Cookware Co.,Ltd of Jiangmen City , https://www.shangwey.com