Take effective measures to prevent and control contamination of edible fungi

Seed production is a key link in the production of edible fungi. In the process of producing strains, improper operation, incomplete disinfection and other reasons will lead to the invasion of miscellaneous bacteria, pollute the strains, reduce the commodity rate of edible fungi and reduce the economic benefits. the common miscellaneous bacteria and control measures in edible mushroom production are introduced as follows:

Penicillium is the most common kind of miscellaneous bacteria. After contamination, it showed a small and separate green powder on the culture medium. Mildew spots. The bacteria are widely distributed and spread by the attachment of conidia in the air to wet materials that have not been thoroughly sterilized. Prevention and treatment measures: ① culture materials should be strictly disinfected. The aseptic operation technique should be strictly mastered when ② is inoculated. ③ strengthens ventilation, cooling and humidity reduction. Local contamination of ④ can be washed with 5-10% lime water.

Second, Trichoderma is mainly green Trichoderma or Trichoderma koningii. It is transmitted by spores produced in organic matter cultures such as decaying wood, seeds, plant residues, compost and soil and floating in the air. The bacteria is acidic, easy to occur when the temperature reaches 25-30 ℃ and the air relative humidity is 80-90%. It can develop from the spot piece to the whole material surface in 3-5 days. Trichoderma is often mixed with Penicillium, the color of their hyphae is similar, the difference is that Penicillium changes from white to green or light yellow, while Trichoderma hyphae begins to be white, turns green or copper green after producing green spores, and deepens gradually. Trichoderma has strong cellulase activity and can decompose cellulose, which mainly occurs in indoor sawdust and other lignin-rich culture medium. Because of its rapid growth, it not only competes with edible fungi for nutrition, but also secretes toxins, so it often forms an "island"antagonistic line" with edible mycelium to inhibit the growth of edible fungus hyphae. Control measures: strict disinfection of ① culture materials, complete elimination of hyphae and spores in culture materials, aseptic operation, strengthening ventilation and cooling. The amount of formaldehyde used in ② disinfection should not be too much to prevent the formation of acidic environment. When there is Trichoderma on ③ medium, apply 755 alcohol, 15% bleach powder, 50% carbendazim 200x solution in time, spray 1-5% lime water or spread white ash powder and then dig, and then smear with lime water. During treatment, it is best to move the strain bag (bottle) outdoors to prevent the spores from flying. After the emergence of Trichoderma, it is strictly forbidden to open the bottle cap or open the film to avoid spread. When using plastic bags to produce seeds, it is not suitable to move too much during the cultivation period. The ungerminated bacteria were removed in time by ④. The cotton stopper of ⑤ strain bottle and strain bag should not be damp, and the culture room should be kept dry and clean. The mother species of ⑥ should be pure. When mixing ⑦, add 25% (or 5%) carbendazim 2 g or 75% tocopherol 1 g per kilogram of dry material.

Third, Mucor, Rhizopus and Aspergillus, also known as Mucor, mainly occur on the initial medium and strains of indoor cultivated mushrooms (ears). The hyphae were white or grayish white at the beginning, and then turned to light yellow. The hyphae are sparse and stout, and the roots can be seen clearly. The greater the water content of the culture material is, the more serious the occurrence is. The ability to decompose starch is strong and grows very fast.

Staggered growth on the material surface, the formation of loose needle-like long hair, after about 3 days, can cover the whole material surface, isolate oxygen, compete for nutrients, water, and secrete toxins, affecting the growth of edible fungi mycelium. After about 40 hours, a large number of black spores can be produced. Rhizopus is similar to Mucor, except that there is no obvious hyphae in the culture material, only the flat substrate grows on the surface, and there is no airborne hyphae. Aspergillus is easy to occur when the water content of the culture material is low and the temperature is high. The hyphae were white cotton wool at the initial stage, and then turned to yellow. When the temperature was above 27 ℃, a large number of spores were produced. Due to different strains, there were black, yellow-green, orange, orange and red colors, and spread very fast. Mucor, Rhizopus and Aspergillus are widely distributed, and spores are found in soil, fertilizer and air. Prevention and treatment measures: ① thorough disinfection, sterilization, do a good job of aseptic operation. When mixing ②, add 2 grams of 25% (or 5%) carbendazim or 1 g of 75% methyl topiramate per kilogram of dry material.

Fourth, Streptomyces is also called Neurospora, which can be harmful in the production process of all levels of bacteria. It is easy to happen especially when the temperature is high and the humidity is high. The bacteria is widely distributed in nature, and all kinds of organic matter, such as corncob, cornstalk, cottonseed hull, waste cotton and so on, are easy to occur. Its conidia float everywhere. When it settles to the surface of organic matter, the hyphae germinate quickly. The hyphae spread quickly, showing gray or yellowish white at first, slender, growing rapidly downward and growing on the cotton stopper. Outside the cotton plug, a large number of pink conidia are formed, which are piled up into clusters with a thickness of about 1 cm, so they are also called powdery mildew. At the slightest shock, the spores are scattered into the air and spread everywhere. Prevention and control measures: ① should do a good job in environmental sanitation, and waste culture materials should be buried deeply. ② culture materials are thoroughly sterilized, cotton plugs should not be damp, and should be replaced in time after dampness. The strain bottle (bag) should be undamaged. The ③ inoculation room should be thoroughly disinfected and strictly abide by the aseptic operation rules. Spread lime on the ④ floor and lime on the tampon at the mouth of the bottle if necessary to keep dry. After discovery, it was removed, burned, and sprayed with 75% wettable topiramate 500 times, or fumigated with 10 ml formaldehyde per m ~ 3 space.