Control methods of competitive mixed bacteria of Edible Fungi

1. Harmfulness of competitive mixed bacteria of Edible Fungi

In the process of edible mushroom production, due to large-scale cultivation or production in the same place for many years, edible fungus diseases and insect pests and miscellaneous bacteria often occur, which spread quickly and lose a lot, which has become a major obstacle to the development of edible mushroom production.

Among them, competitive miscellaneous bacteria, such as bacteria, Trichoderma, Mucor, Rhizopus, Aspergillus and Streptomyces, often occur, infect the mycelium of edible fungi, grow fast, compete for nutrients of culture materials, secrete toxins, and inhibit the normal growth of edible fungi mycelium, resulting in the pollution of strains and bags, and the rate of finished products decreased. Some competitive bacteria also infect the fruiting body, causing diseases. Due to the infection of these competitive miscellaneous bacteria, the contamination rate of bacterial bags can be 10%-20%, some as high as 30%, and the loss is serious. In many cases, the harm of competitive miscellaneous bacteria has exceeded the harm of diseases and insect pests of edible fungi, and has become an important issue that must be seriously solved in the production of edible fungi.

two。 Analysis on the causes of competitive miscellaneous bacteria in edible fungi

The occurrence and spread of competitive miscellaneous bacteria of edible fungi is caused by many factors. The main reasons are as follows.

2.1 bacteria pollution. During the production of bacteria, it was operated carelessly, resulting in miscellaneous bacteria pollution. During the period of strain culture, if not checked in time, the mycelium growth of edible fungi covered up the miscellaneous bacteria, and the strains with miscellaneous bacteria were cultivated. Transfer with this strain will cause batch bacterial bag pollution.

2.2 the production site has been replanted for many years. In the continuous cropping culture room and mushroom room, there is a lot of miscellaneous bacteria accumulation, and there is no thorough control, which is most likely to lead to bacterial bag miscellaneous bacteria pollution.

2.3 the proportion of culture materials is unreasonable. Too much water content of culture materials, too many carbon sources, too few nitrogen sources and imbalance of carbon-nitrogen ratio can easily lead to miscellaneous bacteria infection.

2.4 the culture material was not sterilized thoroughly. Most of the strains and cultivation materials of edible fungi are sterilized by thermal steam. Sterilization is required to reach a certain temperature and pressure, and to maintain a certain period of time. If it does not meet the technical requirements, the sterilization of the culture material is not complete, there are miscellaneous bacteria in the material, and the conditions are suitable, the miscellaneous bacteria will grow out and pollute the bacterial bag.

2.5 pollution during vaccination. When the strain and bag are transferred, the inoculation room (or inoculation box, inoculation account) is not disinfected or not thoroughly disinfected, the environment is infected with bacteria, and there is no aseptic operation, and the miscellaneous bacteria enter the bottle or bag with the inoculation, grow and multiply, causing pollution.

2.6 pollution during the culture period. In addition to the above reasons, the pollution of the bacterial bag during the culture period is also closely related to the thickness and quality of the bacterial bag, the environmental conditions of the culture room and the disinfection of the culture room.

The quality of the bacterial bag is poor, there are micropores, and miscellaneous bacteria enter through the micropores, which is one of the main causes of bacterial bag pollution. The culture room is not ventilated, high temperature and high humidity, which is easy to cause pollution. During the culture period, there are few times of dumping bags, and the contaminated bacteria bags are not eliminated in time, which is easy to cause cross-infection of miscellaneous bacteria.

The culture room has been used for many years, there is a lot of miscellaneous bacteria accumulation, and there is no drug control, the bacteria bag is easy to be infected by miscellaneous bacteria.

2.7 pollution in the mushroom stage. The mushroom room is not sterilized with chemicals, and it is hot and humid, and the bacteria bags are easy to be contaminated. This is especially true in the old mushroom house.

2.8 the difference of disease resistance of varieties. There are some differences in disease resistance among different varieties, for example, Beijing Auricularia auricula is more resistant to miscellaneous bacteria than other Auricularia auricula.

3. Comprehensive Control of competitive mixed bacteria of Edible Fungi

The principle of prevention and comprehensive control should be adopted for the prevention and control of competitive miscellaneous bacteria of edible fungi. Before the infection of miscellaneous bacteria, comprehensive preventive measures should be taken to prevent it from happening and reduce infection. If there is already a large amount of pollution, it will be more difficult to prevent and control it.

The main measures of prevention and comprehensive prevention are as follows.

3.1 excellent varieties with disease resistance, impurity resistance and high yield were selected.

3.2 ensure that the strain is pure. This is the prerequisite for pure culture of edible fungus mycelium. In the whole process of seed production, aseptic operation should be carried out. Inoculation rooms and vaccination tools should be disinfected. Turn on the ultraviolet light to sterilize for half an hour, and spray chemicals or chemical fumigation to ensure that the inoculation environment is free of bacteria. When inoculating, it should be operated in the sterile area above the alcohol lamp flame.

Using Bijieshi compound disinfectant (chlorine dioxide) fumigation inoculation room (inoculation box, vaccination account) is one of the choices. Bijieshi compound disinfectant can be widely used in inoculation room, inoculation account, inoculation box, culture room and mushroom disinfection.

During the period of strain culture, it is necessary to check frequently and eliminate contaminated bacteria at any time. The first-class species should be checked twice during the culture period, and the second-and third-class species should be checked for two or three times.

Attention should be paid to the bacterial age, which is used to produce the transferred strains. The best preservation period of the primary species is within 1 month, and the best preservation period of the secondary and tertiary species is within 20 days. The longer the age of bacteria, the greater the probability of pollution.

For example, during mycelial culture, the C ∶ N ratio of main mushroom species was 17 ∶ 1 for ∶ bisporus, 20 ∶ 1 for Pleurotus ostreatus, straw mushroom and Auricularia auricula, and 25 ∶ 1 for hericium Erinaceus and 25 ∶ 1 for Lentinus edodes. During the mushroom emergence period, the carbon source of each mushroom species should be increased. The suitable moisture content of cultivated materials is 60%, and the ratio of material to water is 1 ∶ 1.1-1.2.

3.4 the culture material should be sterilized thoroughly. Sterilization under atmospheric pressure (100 ℃) takes 10 to 16 hours or more. The high pressure sterilization pressure reached 126 ℃ and kept for 2-4 hours.

3.5 Management of strain and bag culture period. The culture room and training workshop shall be fumigated with chlorine dioxide compound disinfectant for 4 hours, fumigated with 0.3 g / m2, the position height of the drug should be 50 cm ~ 80 cm, the air relative humidity should be higher than 50%, and the dark and airtight condition should be maintained. Fumigation again the next day can achieve twice the result with half the effort.

During the culture period, the temperature of the culture room (culture workshop) should be controlled at 20: 24 ℃.

The relative humidity of the air is kept at 30%-60%. It is often ventilated and cultivated in the dark. Check the bacteria or pour the bags for 2 or 3 times during the culture period, and eliminate the contaminated bacteria and bags in time. Some production units adopt the double-bag method, which greatly reduces the pollution rate.

3.6 Management of mushroom emergence period. Before using the mushroom room, fumigate with chlorine dioxide compound disinfectant, the method is the same as above. Cover the straw curtain and fumigate away from the light. The amount of medicine used in the old mushroom room should be increased by 0.4 to 0.5 grams per square meter.

During the period of mushroom emergence, according to the growth needs of different mushroom species, careful management should be made to maintain suitable temperature, relative humidity, scattered light and ventilation conditions.