Culture Medium For Growing Mushrooms

In bioscience and microbiology research, culture medium, as the basic carrier for microbial growth and reproduction, is prepared with critical steps such as sterilization and mixing. This article will help you understand the preparation of suitable culture medium and provide a complete set of media cultivation solutions, from media configuration to the successful cultivation of edible mushrooms with good quality and stable yield.

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Which medium for growing mushrooms is needed for cultivation?

 

In actual mushroom cultivation, instead of the solid agar medium commonly used in laboratories, solid substrates rich in organic matter are used to cultivate mushrooms. These solid substrates are usually composed of agricultural waste, wood processing by-products or grain processing residues, etc., which are properly formulated and treated to serve as the basic environment for mushroom growth.

 

For example:

1. wood chips: it is the main substrate material for cultivating common edible mushrooms such as shiitake, flat mushroom, almond abalone mushroom, etc. It can be wood chips of broad-leaved tree species or coniferous tree species.

2. cottonseed husk: commonly used in the cultivation of enoki mushrooms, straw mushrooms and other varieties, because it is rich in nitrogen source, which can provide good nutritional conditions for mycelium.

3. corn kernel: after crushing and processing, corn kernel can be used as an excellent culture substrate for mushrooms such as Agaricus bisporus.

4. wheat bran, soybean meal: as supplementary carbon and nitrogen sources of auxiliary materials, often mixed with wood chips or other major substrates.

5. straw, corn stover: can also be used as substrate components for some mushroom cultivation after composting.

 

The use of these mediums for growing mushrooms offers a variety of benefits, including but not limited to:

 

1. providing mushrooms with nutrients needed for growth, including carbon, nitrogen, and trace elements, which help promote rapid growth and development of mushroom mycelium.

2. able to maintain appropriate humidity, providing favorable environmental conditions for mushroom growth.

3. provides the support needed for mushroom growth, enabling them to grow and develop stably. The supportive role of the medium is especially important for some species of mushrooms that need to grow in three-dimensional structures.

4. Many culture media can be prepared from waste or inexpensive resources, such as wood chips, straw, wheat bran, etc., which can help to reduce the waste of resources and at the same time improve the efficiency of resource utilization.

5. Suitable culture medium can help to inhibit or exclude some possible pathogenic microorganisms, reduce the occurrence of diseases during the growth of mushrooms, and ensure the healthy growth of mushrooms.

 

How to Making Substrate For Mushrooms?

 

Material Preparation

Use containers of appropriate size, such as plastic bags, plastic buckets or bottles, etc., for containing the culture medium and mushroom strains. Make sure the container has proper aeration.

 

Mixing

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In the case of wood shavings, for example, place the wood shavings in a large container and add an appropriate amount of water so that they are well moistened but not overly wet. Typically, the ratio of water to wood chips is 1:2 to 1:5.

 

Add lime powder to adjust the pH to a suitable range (usually between 5.5 and 6.5) and a mineral supplement such as gypsum powder or potassium phosphate, as appropriate. Make sure the substrate is moist but not overly wet.

 

If desired, add other supplementary materials such as wheat bran and corn stalks to improve the texture and nutrient content of the medium.

 

Mix well and let it sit for some time to fully absorb the water.

 

Type Wood Chip Medium Straw Medium Cow Manure Straw Medium
Recipe Miscellaneous wood chips 77.5%, wheat bran 20%, sucrose 1%, gypsum powder 1.2%, magnesium sulfate 0.3%. pH value (before sterilization) 6.5–7, water content adjusted to 60%. Corn stover 80%, bran 15%, lime powder 3%, pH (before sterilization) 6.5–7, gypsum powder 2%, water content 60%. Dried cow dung 50%, straw meal (corn stover, rice straw, etc.) 30% (needs to be pre-treated first, e.g., crushed, soaked, steamed), ambrosia/rice bran/soybean meal meal (supplemented with nitrogen source and micronutrients) 16%, lime powder 3%, superphosphate/gypsum powder 1%, and water content 60%.
Mushroom type Suitable for many kinds of edible mushrooms, such as shiitake mushroom, flat mushroom, reishi mushroom, monkey head mushroom and so on. Used for growing flat mushrooms, double spore mushrooms, large globe cap mushrooms and other kinds of mushrooms. For cultivation of edible mushrooms that require high nitrogen source such as Agaricus bisporus, Agaricus cocktail, Agaricus blazei, etc.

 

Mixing, as an important part in the process of mushroom cultivation, is not only related to the quality and applicability of the medium, but also directly affects the growth and yield of mushrooms. Therefore, it is important to take the mixing operation seriously and adopt appropriate measures and techniques to ensure the smooth progress of mushroom cultivation.

 

Sterilization

 

The prepared medium is heated to the appropriate temperature to kill any harmful microorganisms that may be present. This can usually be done using methods such as steam sterilization or high temperature baking. Ensure that the culture medium maintains sufficient humidity during treatment to avoid over-drying.

 

Steam Sterilizer

 

Steam sterilization is the most popular method when it comes to choosing sterilization. Autoclaves can be found in every microbiology lab, every medical facility, dentist, tattoo parlor, quiz labs, food processing facilities, and mushroom farms. While there are many different methods of sterilization, autoclaves are one of the most effective and safest options.

 

Autoclaves utilize superheated steam to infiltrate and sterilize samples placed in them. At standard atmospheric pressure, water boils at 100°C, but if the pressure increases, so does the boiling point. This principle allows the autoclave to generate superheated steam.

 

The autoclave is a pressure rated chamber in which the material to be sterilized is placed and the autoclave is filled with water and then sealed. When the water inside is heated, it begins to boil, creating pressure in the chamber, this pressure increases the temperature that the remaining water must reach to turn into steam, so we have a pressurized chamber with superheated steam.

 

Typically, autoclaves operate at 121°C and 15 PSI, or 135°C and about 30 PSI. this is quite a lot of heat and pressure, so it is a very effective way to penetrate surfaces and sterilize media.

 

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Why do mushroom culture medium need to be sterilized?

 

Autoclaves play a vital role in the cultivation of mushrooms.

1. substrates used for mushroom growth (e.g. mixtures of sawdust, straw, etc.) need to be autoclaved to ensure the elimination of potentially competing microorganisms and to provide a clean, contaminant-free environment for the colonization of mushroom mycelium.

2. All kinds of equipment and tools used in cultivation, including containers, trays and operating tools, etc., also need to be strictly autoclaved and disinfected before use to prevent the introduction and spread of pathogenic microorganisms.

3. In the production of mushroom strains, the mycelial growth medium is also treated with the aid of autoclaving techniques. Autoclaving is essential to maintain aseptic conditions during the laboratory stage of research and development of new strains to ensure accurate and reliable experimental results.

4. By applying autoclaves consistently throughout the cultivation cycle, contaminants can be effectively controlled, the impact of harmful microorganisms on the mushroom crop can be minimized, and standardization and quality control of the entire process can be ensured, resulting in the harvesting of high-quality mushroom products.

 

Items that can be autoclaved

Bulk substrates

Agar

Liquid cultures

Glassware

Tools and labware

Tubes and Equipment

Bags and Jars

Scrap material

 

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How to choose a sterilizer for mushroom culture medium?

 

When choosing a sterilizer for sterilizing mushroom media, it is very important to select the right sterilizer based on the size of the production because the size of the production has a direct impact on the amount and frequency of media you need to treat.

 

Medium-scale Production (Medium-sized Laboratory or Small-scale Commercial Production)

 

Medium scale production usually requires the processing of a larger volume of culture media. As a result, you may need to choose a sterilizer with a larger capacity, usually between tens and hundreds of liters.

 

This type of equipment usually has a more moderate volume, which can meet the needs of sterilizing a certain batch of culture medium without taking up too much space and energy resources. For sterilizing mushroom media, an efficient vertical autoclave with a moderate capacity can significantly increase productivity.

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Mushroom Sterilizer

 

The machine’s double basket design and vertical loading doubles the amount of media that can be processed per unit of time, reducing cycle times and waiting times.

 

For materials such as grain bags that are easily stacked and deformed or compressed, it is necessary to leave appropriate “breathing space”, and glass jars, ceramic cups, etc. can be skillfully used as a spacer to ensure uniformity of the gap between the items. Overloading is rejected.

 

Precise temperature and pressure control systems ensure stability throughout the sterilization process, eliminating the need to guess the duration of sterilization and effectively eliminating uncertainty.

 

Setting timers and auto-stop functions through the built-in digital controller simplifies the management process of large-scale sterilization operations.

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Overall, choosing a vertical autoclave with an intelligent control system enables a more efficient, accurate and safe media sterilization process in medium to large-scale mushroom production, optimizing overall productivity and quality.

 

Large-scale Production (Large Commercial Production)

 

Large scale mushroom production environments require large sterilizers that are efficient and capable of handling large quantities of media. This requires the selection of large capacity sterilization equipment, typically in the range of hundreds to thousands of liters.

 

These are typically industrial grade autoclaves and are designed with automated control systems to increase efficiency and reduce labor costs. Large continuous or batch autoclaves are ideal for this purpose, as they are not only able to sterilize large quantities of media quickly, but also have good stability and durability for long term, high load operating conditions.

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Mushroom Substrate Sterilizer

 

Workflow:

1. Prepare the medium: fill the prepared mushroom medium into the culture container, make sure the container is sealed and leave enough space for the medium to expand during the sterilization process.

2. Load into steam sterilizer: Put the container with culture medium into the steam sterilizer, make sure that the container is firmly placed to avoid moving or tipping over during the heating process.

3. Adjusting parameters: Set the operating parameters of the sterilizer, including pressure, temperature, and hold time.

4. Execute the sterilization process: When the equipment reaches the set pressure and temperature, start the timer and maintain it for a specified period of time to allow the high temperature steam to fully penetrate into the culture medium and kill all potential microorganisms. The duration is usually between 30 minutes and 1 hour, depending on the type and volume of the medium.

5. Cooling and pressure release: After sterilization, the door lock should not be opened immediately, and the internal pressure of the sterilizer should be reduced to atmospheric pressure through natural cooling or fan-assisted cooling. Some models of sterilizers have automatic pressure relief function.

6. Removal and storage: When the pressure gauge indicates zero, and the temperature is suitable for the operator to contact, the lid of the sterilizer can be slowly opened to remove the culture medium containers that have been sterilized and transferred to a clean environment for storage or subsequent inoculation in accordance with aseptic operating procedures.

7. Quality check: In order to verify the sterilization effect, biological indicators (such as thermophilic Bacillus spores) can be placed in the sterilized batch to observe whether they survive to confirm the success of sterilization.

 

When selecting sterilization equipment, in addition to considering the scale of production, you should also consider your budget and available space to ensure that the selected equipment can meet the stringent requirements of mushroom media sterilization, but also to maximize the economic benefits. The sterilizer chosen also needs to be able to meet not only current production needs, but also future expansion needs.

 

Inoculation

 

Inoculation of mycelium is one of the key steps in the mushroom cultivation process. After the medium has cooled down sufficiently, mushroom strains are introduced into the medium to promote the growth of mycelium and the formation of mushroom bodies. Usually, the bag culture method is used, in which the mixed mycelium and medium are put into a plastic bag, and then the mouth of the bag is tied tightly or closed with a clip.

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The following are the general steps for inoculating mycelium:

 

1. Prepare the culture medium: Make sure that the medium has been sterilized and cooled to a suitable temperature. Usually, the medium should be cool before inoculating the mycelium to avoid harming the mycelium.

2. Prepare the strain: Prepare the mushroom strain, usually a block of mycelium cultured in the medium or spores from the medium. Ensure the purity and vigor of the strains to promote the rapid growth of mycelium.

3. Inoculation medium: Disperse the prepared strains evenly on the surface of the medium or mix them into the medium. Inoculation can be carried out by placing blocks of strains directly on the surface of the medium or by dispersing them in the medium and mixing them gently.

 

Containers with medium and mycelium are placed under suitable environmental conditions for cultivation. Mushrooms usually need to be grown in an environment with high temperature and humidity. During the incubation process, it is necessary to check the humidity and mycelial growth inside the container periodically to ensure that the incubation conditions are stable and appropriate.

 

Incubation

 

When the mycelium grows sufficiently in the medium and forms mycelial clumps, subsequent treatments can be carried out. This usually includes measures such as increasing ventilation and regulating humidity to promote mycelium formation and mushroom production. When the mushrooms begin to grow and mature, they can be picked and harvested.

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Conclusion

Mushroom cultivation is not only a technical endeavor, but also an art that requires patience and care. In mushroom cultivation, mixing and sterilizing are critical steps to ensure clean media and mycelial growth. By mixing the medium, the demand for various nutrients of a specific mushroom strain during its growth and development is met, promoting good mycelial growth. By properly executing the sterilization procedure, we can effectively eliminate potentially harmful microorganisms and create a good environment for the healthy growth of mushrooms.

 

Cultivating quality mushroom products also requires continuous efforts and experience. Only by constantly improving and refining cultivation techniques can we achieve better harvests and quality to meet market and consumer demands. The medium used to grow mushrooms is designed to create an optimal growing environment for edible mushrooms, ensuring their healthy and rapid growth and enhancing the overall economic and ecological benefits.

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