What are the bacterial culture media? medium
1. According to mediumAccording to its components, it can be divided into three categories: synthetic medium, natural medium and semi-synthetic medium.
(1) Synthetic medium. The various components of synthetic medium are completely known chemical substances. The chemical composition of this medium is clear, the composition is accurate, and the repeatability is strong, but it is more expensive, and microorganisms grow slowly in this type of medium. Such as Gao's No. 1 synthetic medium, Czapek medium, etc.
(2) Natural medium. Made of natural substances, such as steamed potatoes and ordinary beef broth, the former is used to cultivate mold and the latter is used to cultivate bacteria. The chemical composition of this type of medium is very variable and difficult to determine, but it is easy to prepare and rich in nutrients, so it is often used.
(3) Semi-synthetic medium. Appropriately add inorganic salts of known ingredients on the basis of natural organic matter, or add certain natural ingredients on the basis of synthetic medium, such as potato glucose agar medium for mold culture. This type of medium can more effectively meet the nutritional needs of microorganisms.
2. According to the physical state of the medium
Media can be divided into solid medium, liquid medium and semi-solid medium according to their physical state.
(1) Solid medium. Coagulant is added to the medium, including agar, gelatin, silica gel, etc. Solid medium is often used for microbial isolation, identification, counting and (2) Liquid medium. No coagulant is added to the liquid medium. The composition of this medium is uniform, and microorganisms can fully contact and utilize the nutrients in the medium. It is suitable for physiological research. Due to its high fermentation rate and convenient operation, it is also commonly used in the fermentation industry.
(3) Semi-solid medium. It is a semi-solid state by adding a small amount of coagulant to the liquid medium. It can be used to observe the movement of bacteria, identify bacterial species and determine the titer of phages.
3. According to the type of microorganisms
According to the types of microorganisms, the culture medium can be divided into four categories: bacterial culture medium, actinomycete culture medium, yeast culture medium and mold culture medium.
Commonly used bacterial culture medium includes nutrient broth and nutrient agar medium; commonly used actinomycete culture medium is Gauss No. 1 medium; commonly used yeast culture medium includes potato sucrose medium and malt juice medium; commonly used mold culture medium includes potato sucrose medium, bean sprouts juice glucose (or sucrose) agar medium and Chastella medium.
4. According to the purpose of the medium
Media can be divided into enrichment medium, selective medium and identification medium according to their special uses.
(1) Enrichment medium. It is to add blood, serum, animal and plant tissue extracts to the medium to cultivate certain microorganisms with more demanding requirements.
(2) Selective medium. It is a medium designed according to the special nutritional requirements of a certain type of microorganisms or some physical and chemical resistance. This medium can be used to separate the required microorganisms from the mixed microorganisms.
(3) Identification medium. It is the addition of certain reagents or chemicals to the medium to cause certain changes to occur after cultivation, thus distinguishing between different types of microorganisms.
Media precautions:
Confirm whether the working cell bank is contaminated, confirm whether the working seed batch of poison seeds is contaminated, and confirm whether the medium used and its added ingredients (such as calf serum, NaHCO3, etc.) are contaminated. Bacteria, fungi and mycoplasma sterility tests can be used to confirm and rule out. At the same time, the sensitivity of the sterile test medium should be verified. In actual production, a small amount of nutrient agar can be taken from the prepared medium and cultured in a constant temperature incubator, and pollution can be observed within 48 hours.
Other: Autoclaving equipment and filtration sterilization equipment should be verified to ensure sterilization and sterilization effects; the former should be verified before and every 6 months after production, and the latter should be verified before and after each sterilization (at least once after sterilization).
In addition, the toxic area should be strictly separated from the non-toxic area, and have their own independent air purification system and incubator. The toxic area should maintain a relatively negative pressure on the non-toxic area to prevent virus contamination of cultured cells (especially cell banks).
