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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 enrichment medium, the identification medium, and the like; may be classified into a bacterial culture medium, an actinomycete culture 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 filter sterilization. The medium is easily contaminated or deteriorated due to its rich nutrients. It should not be placed for a long time after being equipped. It is best to use it now.
Medium preparation process
1. Conversion of ingredients and formulas → 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. Dissolved starch dissolve: a small amount of cold water is adjusted into a paste. Heat to dissolve, especially the medium with agar, be sure to boil, the melting temperature of the agar
95-97 ° C, and need 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 the filter paper or cotton for filtration. (sometimes can be omitted) [4]
5. Dispense the general culture medium in a triangular flask or test tube for sterilization.
(1) If the flask is used for static culture, 100ml medium/250ml flask, zui can not exceed 150ml medium/250ml triangle bottle, otherwise the medium will boil easily contaminate the tampon during sterilization, causing bacteria; For shake flask culture, a 15-20 ml medium/250 ml flask is used to ensure good ventilation.
(2) The test tube is divided into 4-5 ml of liquid medium, about 1/4 of the height of the test tube; the solid slant medium is usually 3-4 ml, about 1/5 of the test tube.
6. After the dressing is completed, the cotton plug is stuffed, and the cotton plug is wrapped in kraft paper to prevent moisture from entering the cotton plug when it is sterilized.
7. Sterilization High-pressure steam sterilization is carried out according to the temperature and pressure required on the formulation. If the temperature of sterilization is too high, the nutrients will be destroyed, and the sugar and amino acids in the medium will make the color of the medium darker.
8. After the inclined surface is sterilized, the test tube that needs to be inclined is placed obliquely and hot, and it is solidified into a slope, which is about 1/2 of the length of the test tube.
The medium was allowed to stand at 30 ° C for one day and was used without contamination. Usually wrapped in kraft paper and stored in a 2-8 ° C refrigerator in the spare medium prepared, why must be sterilized immediately?
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. In order to achieve the purpose of the experiment and research, it is formulated according to the formulation of the medium. Any medium, once prepared, should be thoroughly sterilized 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, causing the reaction to be abnormal; some bacteria will decompose the product and cause the production to fail; When 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 it grow as fast as possible or produce metabolites, so they are allowed to grow on the zui suitable medium to reduce the cultivation time and improve the economic benefit.
Which type of high pressure steam sterilization is used, it is recommended that the ALP autoclave is imported, has strong sterilization effect, high safety, vacuum drying function, exhaust function and long service life (has been used by customers for more than 15 years). "Imported Pressure Vessel Production License", "Import and Export Boiler Pressure Vessel Safety Performance Inspection Certificate", "Metrics Certificate" and other complete sterilizers.
The ALP autoclave switch is easy and simple, and the electronic lock can only be turned on when power is on to avoid accidental leakage of unsterilized material due to power failure or shutdown. The autoclave clearly shows 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 autoclave quickly dries the sample through a vacuum pump and hot air filtered through a 0.2um filter to make it fast and available. 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 best price, fast delivery and excellent service. Take the imported Japanese ALP autoclave as an example. The product is represented by Southeast Scientific Instrument Company.
Medium Preparation and Sterilization Guide
The culture medium needs to be sterilized immediately after the preparation of the culture medium, and 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.