Medium refers to a nutrient substrate prepared by the combination of different nutrients for the growth and reproduction of microorganisms, plants or animals (or tissues). Generally, it contains carbohydrates, nitrogenous substances, inorganic salts (including trace elements), vitamins and water. The medium is not only the basic material for providing cell nutrition and promoting cell proliferation, but also the living environment for cell growth and reproduction.
There are many kinds of culture media, which can be divided into natural medium, synthetic medium and semi-synthetic medium according to the source of the prepared raw materials; according to the physical state, it can be divided into solid medium, liquid medium and semi-solid medium; The basal medium, the selection medium, the rich medium, the identification medium, etc.; can be classified into a bacterial medium, an actinomycete medium, a yeast culture medium, a fungal culture medium, and the like according to the use range.
After the medium is formulated, it is generally required to test and adjust the pH. It must also be sterilized, usually by high temperature sterilization and filtration sterilization. The medium is easily contaminated or deteriorated due to its rich nutrients. After the match is not suitable for a long time, Zui is now ready to use.
Medium preparation process
Ingredients
Formulation conversion → Add a small amount of water (distilled water, natural water) to the container → Weigh all kinds of medicines according to the formula (in order) → add enough water (one spoonful of medicine, cover the bottle immediately after taking the medicine).
2. Dissolve
Starch dissolution: a small amount of cold water is adjusted into a paste. Heat to dissolve, especially the medium supplemented with agar, must be boiled, the melting temperature of the agar is 95-97 ° C, and it is necessary to stir while heating to prevent charring.
3. Adjust PH
The medium was adjusted to the desired value with 1 N hydrochloric acid or 1 N NaOH.
4. Filter
Filter paper or cotton for filtration. (sometimes can be omitted) [4]
5. Packing
The medium is usually sterilized in a triangular flask or test tube.
(1) Triangle bottle
For static culture, 100ml medium / 250ml triangle bottle, up to 150ml medium / 250ml
Triangular bottle, otherwise the medium boiling during sterilizing will easily contaminate the tampon, causing bacteria; if it is shake flask culture, 15-20ml medium/250ml triangle bottle will ensure good ventilation.
(2) Test tube dispensing
The liquid medium is generally loaded with 4-5 ml, about 1/4 of the height of the test tube;
The solid slant medium is usually loaded with 3-4 ml, about 1/5 of the height of the test tube.
6. Bandaging
After the parts are packed, plug the cotton plug and wrap the cotton plug with kraft paper to prevent moisture from entering the cotton plug when it is sterilized.
7. Sterilization
Autoclave sterilization according to the temperature and pressure required by the formulation. If the temperature of sterilization is too high, nutrients will be destroyed and cultured.
The sugars and amino acids in the base make the color of the medium darker.
8. Pendulum
After sterilization, the test tube that needs to be inclined should be placed obliquely and hot to make it a bevel, about 1/2 of the length of the test tube.
9. Storage
The medium was allowed to stand at 30 ° C for one day and was used without pollution. Generally wrapped in kraft paper and stored in a refrigerator at 2-8 ° C
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Why do I have to sterilize immediately after the medium is prepared ?
As we all know, the medium is a mixed nutrient for the growth, reproduction and metabolism of microorganisms. Because microorganisms have different types of nutrients, the requirements for nutrients are also different. In addition, the purpose of experiments and research is different, so there are many kinds of culture media, and the raw materials used are also different. For the purposes of the experiments and studies, it is formulated according to the formulation of the medium. Any medium should be thoroughly sterilized in time for preparation for pure culture. The sterilization of the general medium is autoclaved .
During the fermentation process, the medium is sterilized mainly for the following reasons: if it is not sterilized, the matrix or product of the biological reaction will be lost due to the consumption of the bacteria, resulting in a decrease in the production capacity; the bacteria will also produce metabolites. This makes the extraction of the product more difficult, resulting in lower yield and lower product quality. After the bacteria are multiplied, the pH of the reaction solution will change, making the reaction abnormal; some bacteria will decompose the product and cause production failure; If the phage is contaminated, the producer cells will be lysed and the production will fail.
Sterilization of the medium is to kill the original bacteria in the medium or the bacteria attached to the air, to better grow the target bacteria (reducing the nutrients in the medium consumed by the bacteria, and some bacteria will inhibit your target bacteria) Growth). Generally, artificial culture bacteria basically make them grow as fast as possible or produce metabolites, so they are allowed to grow on the optimum medium to reduce the cultivation time and improve the economic efficiency.
Which type of high pressure steam sterilization is used, ALP autoclave is recommended
Original imported, strong sterilization effect, high safety, vacuum drying function, exhaust function, long service life (has been used by customers for more than 15 years), is equipped with "imported pressure vessel production license", "import and export boiler pressure Completely sterilized certificates such as the Container Safety Performance Inspection Certificate and the Measurement Certificate.
The ALP high pressure steam sterilizer switch is easy and simple, and the electronic lock can only be turned on when the power is turned on to avoid accidental leakage of unsterilized substances due to power failure or shutdown. The autoclave clearly displays the status, such as temperature, pressure, procedures, and other relevant information during operation. The pulsed air purification of the autoclave is repeated until the pressure is higher than the corresponding temperature to produce a supersaturated vapor pressure to ensure the sterilization effect. The high-pressure steam sterilizer adjusts the steam discharge according to the condition of the sterilized material. The high-pressure steam sterilizer has a rapid cooling function to quickly cool down to a safe temperature below 80 °C after sterilization. The ALP high pressure steam sterilizer quickly dries the sample through a vacuum pump and hot air filtered through a 0.2 um filter to make it available quickly. The high temperature steam sterilizer comes with a temperature probe mounting hole and an optional temperature probe for easy verification of the internal sterilization effect. The triple pulse of the autoclave sterilizer, the pre-vacuum device is equipped with a powerful vacuum pump forcibly venting the air retained in the cavity, so that the saturated steam penetrates well into the sterilized article, thereby ensuring sufficient and effective sterilization effect.
Of course, in addition to the above certificates and functional factors, it is also very important to choose the right supplier. Generally, Zui is looking for an agent of the product, which can guarantee the good price, fast delivery and excellent service of Zui. Take the imported Japanese ALP autoclave as an example, the product is represented by Southeast Scientific Instrument Company.
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