What are the commonly used disinfection methods?

Generally speaking, disinfection means that the strain bottles are sterilized at high pressure or normal pressure and then cooled to room temperature. In order to inoculate the pure strain into the strain bottle, it is necessary to create a local relatively sterile inoculation space. Therefore, it is necessary to disinfect the local space by physical or chemical methods to kill most floating microorganisms. In other words, it is to purify the breeding space. In addition, before cultivation, in order to improve the environment of strain cultivation and rod cultivation, especially the space and sanitary conditions of the old mushroom shed and strain farm, it is collectively called disinfection. There are mainly the following disinfection methods:

(1) pasteurization

At the temperature of 60 ~ 66℃, it can kill most nutritional bacteria, such as the post-fermentation process of Agaricus bisporus culture material, and can kill miscellaneous bacteria and pests harmful to mushrooms.

(2) boiling water disinfection

Mainly used for disinfection of metal appliances, syringes, etc. Boiling water for 20 ~ 30 minutes can kill the vegetative body of microorganisms, while killing cell spores takes 1 ~ 2 hours. If a little 2% ~ 5% carbonic acid solution is added to the water, the disinfection time can be greatly shortened; Adding 1% sodium bicarbonate can increase the boiling point of water, accelerate spore death and prevent metal utensils from rusting due to cooking.

(3) drying and disinfection

Dry substances dehydrate microorganisms, thus achieving the purpose of sterilization or bacteriostasis. Microbial cells contain 70% ~ 90% water, and microorganisms will tend to die after losing water. People often use this feature to preserve food (such as dried mushrooms and fungi) and medicine for a long time.

(4) osmotic pressure disinfection

Using high osmotic pressure or low osmotic pressure to sterilize or inhibit bacteria is called osmotic pressure disinfection. Generally, the concentration of salt solution is about 20%, and the concentration of sugar solution is 50% ~ 70%.

(5) chemical disinfection

This is a method of sterilization or bacteriostasis by using chemical reagents. The following are some main types of disinfectants:

Lime: There are quicklime and hydrated lime. Its mechanism is that it can hydrolyze protein and nucleic acid, destroy enzyme system and decompose sugar in bacteria. 1% ~ 3% lime water can play a strong bactericidal role. In the mushroom house and its surrounding environment, quicklime should be used for disinfection, because hydrated lime can absorb carbon dioxide in the air after being exposed to the air for a long time and form calcium carbonate without sterilization.

Stone-sulfur mixture: Bordeaux mixture mixed with lime, often used for disinfection of mushroom houses and bedsteads. Bordeaux mixture is the formula of 100 ~ 200 times of copper sulfate and lime, namely 1 kg of copper sulfate, 1 kg of lime and 100 ~ 200 liters of water. When preparing, firstly, copper sulfate and lime are dissolved in water respectively, and at the same time, they are poured into another wooden bucket or vat, and stirred while pouring, that is, Bordeaux liquid is blue all day. Wooden barrels or ceramic containers should be used when preparing, which should not be stored for a long time. When in use, spray with a sprayer.

Coal phenol soap solution (C6H4CH3OH): It is a surfactant disinfectant, also known as Lysol, which is a soap solution containing 50% coal phenol. Its bactericidal mechanism is the same as that of carbolic acid, its bactericidal effect is four times that of phenol, its irritation to skin is less than that of carbonic acid, and its common concentration is 2% ~ 4%. It is used for disinfection of skin, inoculation room (box), table top, floor and tools of culture room, and is often arranged to be used after fumigation and before inoculation. In addition to its strong bactericidal effect, the coal phenol soap solution also has the functions of settling dust, bacteria and neutralizing formaldehyde gas, making the space cleaner and more comfortable.

Ethanol (C2H5OH): Also known as alcohol. It is a good dehydrating agent, protein denaturant and fat solvent, and 70% ~ 75% ethanol has the best sterilization effect. Anhydrous alcohol and 95% alcohol have low bactericidal power. The reason is that high-concentration alcohol has a strong dehydration effect. When it comes into contact with bacteria, it will immediately solidify the protein on the surface of bacteria, forming a protective film, so that alcohol molecules cannot penetrate further into bacterial cells.

Formaldehyde (CH2O): It has a pungent smell, is soluble in water, and has a strong irritating effect on people's eyes and nose. Formaldehyde solution, also known as formalin, contains 37% ~ 40% formaldehyde, which is corrosive and irritating and is a strong reducing agent. Its sterilization mechanism is to combine with amino group of microorganism protein, so that it coagulates and denatures in protein, thus achieving the purpose of sterilization. 0. 1% ~ 0.25% formaldehyde solution can kill bacteria, spores and viruses within 6 ~ 12 hours. Inoculation rooms (boxes) or culture rooms that have been used for a long time and are heavily polluted can be completely disinfected by mixed fumigation with formaldehyde and potassium permanganate. There are two common methods. One is to mix 6 ~ 10 ml formaldehyde solution with half to the same amount of potassium permanganate per cubic meter of space for oxidation reaction, and release heat to make formaldehyde boil and volatilize. The inoculation room is generally fumigated 12 hour, and the inoculation box is fumigated for 0.5 hour. Another method is to put formaldehyde solution directly on a small electric stove or brazier for heating and evaporation. This method needs supervision, but it works well. Because the water in the process of formaldehyde volatilization is also heated and evaporated, the humidity in the space is improved and the disinfection and sterilization effect is enhanced. After disinfection, the inoculation room should be heated to evaporate the same amount of ammonia water or spray 3% coal phenol soap solution for neutralization after 12 hours, and then wait for 6 ~ 10 hours before entering the operation.

5% formaldehyde solution is also commonly used for antiseptic and surface disinfection of crop seeds; Used for disinfection of instruments, soaked for 1 ~ 2 hours.

Potassium permanganate: purple needle-like crystal, which is a commonly used strong oxidant. Potassium permanganate solution diluted to 0/000 times of 1250 times has bactericidal effect, and 0.5% ~ 1% potassium permanganate aqueous solution can kill most bacteria within 5 minutes; 5% aqueous solution can kill bacterial spores within 1 hour, but the lethality to mold is weak; 0. 1% potassium permanganate aqueous solution is often used to disinfect skin and glassware, but it should be prepared with it. Because potassium permanganate can react with the organic matter in the culture material and be reduced to manganese dioxide without sterilization, it cannot be directly used for sterilization of the mixture.

Bromogeramine: It is a strong cationic surfactant bactericide, which has an aromatic smell, is extremely bitter and easily soluble in water. It has a strong bactericidal effect on spore-free pathogens, molds, etc. The effect is 10 times that of carbonic acid. Disinfection features: fast, thorough and efficient. The concentration of stock solution is 5%, and the common concentration is 0. 1%, which is used for disinfection of skin and metal instruments. Note that it should be used now. It is non-irritating to human body and non-corrosive to instruments, and it is an efficient and non-toxic bactericidal inhibitor.

Sulfur: it is often used for fumigation and disinfection in culture rooms and mushroom houses, and can also be used for killing insects and mites. The dosage is 15 ~ 20g/m3. Because the density of SO2 produced by fumigation is higher than that of air, it is easy to sink. When fumigating, attention should be paid to placing the container containing sulfur in a higher space. In order to improve the sterilization effect, a small amount of water should be sprayed on the wall and space before fumigation to promote the generation of more sulfurous acid and improve the sterilization effect.

Carbendazim: Carbendazim is a broad-spectrum and efficient systemic carbamate fungicide with the characteristics of broad spectrum, high efficiency and long validity. Low toxicity to people and livestock, and the effective period is about 10 day. It is an ideal bactericide commonly used in edible fungi production. However, in use, due to the lack of pesticide knowledge and improper operation of mushroom farmers, the effect decreased. The usage and precautions of carbendazim are briefly described as follows:

① Carbendazim in the market are mostly 50% wettable powder and 40% colloidal suspension, the former is more commonly used. No matter which dosage form you choose, you should buy regular products with reliable quality and good reputation, and use them within one year after leaving the factory. If it is more than one year and still within the validity period, the dosage may be increased as appropriate.

(2) When mixing materials, the concentration of liquid medicine should be strictly controlled. The general dosage of 50% wettable powder is 0. 1% of the dry matter weight. Excessive dosage will not only increase the cost, but also affect the growth of mycelium.

(3) when dissolving powder, pay attention to sufficient water, stir evenly and dissolve completely; When mixing materials, mix the raw materials and medicines evenly.

(4) Carbendazim is easy to decompose and fail in alkaline environment. Therefore, lime should be avoided when mixing materials, and carbendazim and lime should not be used as a mixed solution.

⑤ Carbendazim is resistant to high temperature and is not affected during fermentation and autoclaving.

⑥ Carbendazim is easy to make miscellaneous bacteria resistant, so it should be used alternately with other fungicides to enhance the bactericidal effect.

⑦ Carbendazim has poor control effect on Mucor and Rhizopus, so the pH value of the culture medium should be appropriately increased when it is used to inhibit the growth of Mucor and Rhizopus.

⑧ Tremella, Auricularia auricula and Hericium erinaceus are particularly sensitive to carbendazim and should be avoided when cultivated.

In recent years, with the rapid development of edible fungi industry in various places, the research and production of disinfectants have mushroomed, which have the potential to replace these traditional disinfectants, such as Kemeiwang, Bijieshi and Jingmeiling, so I won't introduce them here.