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Macrolepiota albuminosa: a delicious edible fungus cultivated by termites

Date:2023-7-28 14:56:00   

Collybia albuminosa (Termitomyces albuminosus (Berk) Heim) is a symbiotic fungus with termites in nature. When termites build ant nests, they cultivate the mycelium of Gallus albuminosa to form a common ecosystem.

Most of the fruiting bodies of Collybia albuminosa belong to large species, with a cap diameter of 1-30 cm, or even larger than 50 cm, and a flesh thickness of 1-3 cm. A few are small species, with a cap diameter of less than 1 cm. The large-scale species of the fruiting body of Gallus pilosula is thick and plump, with a length of 1-30 cm and a thick stipe of 0.5-4 (6) cm. The meat is tender and white, and the taste is sweet and crisp. The stipe and cap mushroom meat are rich in protein, fat, and dietary fiber necessary for the human body, as well as a variety of mineral elements, trace elements, multivitamins, riboflavin, amino acids and other substances. It tastes delicious when cooking soup and cooking , the flavor is similar to chicken soup, and it is the crown of fungi.

Collybia albuminosa is actually a type of fungus cultivated by termites in nature. Termites cut and chop wood, branches, leaves, grass stalks, grass blades and other plant materials, and transport them to the nest, plus soil, water, saliva, excretion, etc. The termites live in the ant nest, which is rich in organic matter in the nest body, which provides a variety of nutrient sources for the growth of fungal mycelium, including carbon sources, nitrogen sources, and mineral elements. , growth factors, water, etc. Water is taken by termites from around the ant nest, and transported to the nest body through the specially opened transport channel through which the nest body communicates with the outside world. Generally, the water content of the nest body is 45%-50%, which is much higher than that of the surrounding soil. The water content of the soil will not exceed 25%, and the water content of the plant body is also lower than 50%. It must have external water sources and transportation channels. means of transport.


Figure 1 The fruiting body of Collybia albuminosa growing from the termite nest

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Figure 2 Fruiting body of Collybia albuminosa: cap surface and gills

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Figure 3 Collybia albuminosa young fruiting bodies and clustered fruiting bodies

The environmental conditions for the growth of fungal mycelium in the ant nest, including temperature, air humidity, space carbon dioxide concentration, water content of the nest matrix, and pH of the nest, are all controlled by termites. Ant nests are located a few millimeters to tens of centimeters below the ground, forming a relatively closed environment. Here constant temperature, constant humidity, high carbon dioxide concentration, under the adjustment of formic acid in termite saliva and excrement, the pH of the nest body matrix is lower than 4 and very stable, which can effectively inhibit the growth of most bacteria and molds, and has become some A selective medium for acidophilic fungi, of which Collybia albuminosa belongs, and of course other fungal species that do not produce fruiting bodies that termites prefer. The fungal mycelium decomposes plant materials to generate heat, the termites breathe heat, the nest body is relatively closed, and the surface soil keeps warm, so that the underground ant nest is in a constant temperature state of 18-22°C, which is especially suitable for the rapid growth of fungal mycelium. Fungal mycelium and termite respiration produce a large amount of carbon dioxide. In a relatively closed underground, a high-concentration carbon dioxide environment is formed. The high concentration of carbon dioxide can effectively inhibit the formation of fruiting bodies on the Collybia albuminosa mycelium. Underground nests have no light, and dark conditions can promote the growth of mycelium and effectively inhibit the formation of fruiting bodies of Collybia albuminosa. Of course, the life of termites and the growth of fungi also need a lot of oxygen. When termites build their nests, they will also build some channels to communicate with the outside world above the nests. The soil still has a certain degree of air permeability. The exchange of air between the nests and the outside world is will not be blocked.

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Figure 4 Underground termite nests

With the nutrients and environmental conditions for the growth of fungi, the termite nest becomes a constant temperature incubator and an artificial climate chamber for the growth of fungi. The fungal strains are the undigested mycelium or conidia in the intestines of termites. They migrate to the next site. When building a new nest, they use their excrement as building materials to connect the new nest. strains.

Because the purpose of termites cultivating fungi is to produce a large amount of mycelium, fungal mycelium has become a high-protein, disease-resistant, and easily digestible food for termites, so termites are also creatures that produce and manufacture food by themselves, and they have become the oldest Self-reliant, self-sufficient "farmers".

The mycelium of Collybia albuminosa will grow in large quantities inside the termite nest matrix, decompose various organic matter to form a large amount of mycelium biomass, and then produce a large number of "small white ball" mycelium on the surface of the thin-walled nest body, small The white balls are 200-800 microns in diameter. Termites eat these nutritious white balls and reproduce and grow into a large colony with millions of residents. The pure strain of Collybia albuminosa can be obtained by separating and purifying from the gut of the termite.

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Fig.5 Mycelia of small white balls of Collybia albuminosa

If the fungus cultivated on the termite nest is the mycelium of Collybia albuminosa, when spring comes and thunderstorms pass, the water content of the soil above the ant nest increases, forming an appropriate temperature difference, humidity difference, and air pressure difference, and the nest will form Primordia, primordia grow taller and form rhizoids, which pass through the space above the nest body and enter the soil above the nest body. The water content in the soil is suitable, and the rhizoids quickly grow out of the soil surface to form a stipe, and the top of the stipe forms a fungus build. After the rain, the air humidity is high, which is suitable for the growth of stipe and cap, and a large number of fruiting bodies of Collybia albuminosa will suddenly grow on the soil surface. From May to October, as long as we do not destroy the ant nest, disturb or scare the termites, one ant nest can produce 4-5 batches of mushrooms continuously. Nutrient-rich fruiting bodies of Collybia albuminosa provide delicious food for above-ground insects, other animals, and especially humans. On a very small ant nest with a dry weight of less than 100 grams, more than 500 grams of fresh mushrooms can be collected. This mushrooming behavior will consume a large amount of nutrients that termites need, which is what the termite colony itself does not want to see. The events that come to them are also things that they can't do anything about. It is termites that unwittingly provide us humans with delicious food.

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Figure 6 The stipe of Collybia albuminosa growing on the ant nest

Because the size and nutrients of a termite nest are limited, the number of natural wild Collybia albuminosa fruiting bodies is very limited, which cannot satisfy people's unlimited food needs. People always want to domesticate and commercialize Collybia albuminosa, and cultivate the fruiting bodies of Collybia albuminosa under artificial conditions. However, it is very difficult to artificially produce Collybia albuminosa on a large scale. Although we can easily isolate the pure strain of Gallus albuminosa, the difficulty is that the growth of Collybia albuminosa mycelium on artificial medium is very slow, and it can be cultured on various nutrient-rich agars. Basically, the growth length of a month is less than 1 cm, and it takes half a year to grow a small triangular flask on a solid medium. It is inevitable to pollute for a long time, so the production of edible fungi is based on conventional methods. method is not working. A feasible method is to artificially cultivate a large number of termites. After the termites are reproduced on a large scale under controllable and non-fleeing conditions, the moisture and temperature and humidity of the soil above the ant nest can be well managed, and small-scale artificial cultivation of Collybia albuminosa can be realized. However, termites are well-known harmful insects that damage various wooden structures such as furniture, buildings, books, leather, natural materials, textiles, wooden coffins, artificial dams, civil structures, wooden floor doors and windows, trees, etc. Termites are extremely powerful and must be strictly controlled and killed. Artificial breeding of termites must not allow them to escape.

In real life, we often refer to termites as "white ants". In fact, termites and ants belong to the order Blattata and Hymenoptera in the classification system of Insecta. Termites have a living history of 250 million years, while ants have a living history of only 60 million years. From the perspective of biological evolution, termites are relatively ancient and primitive insects. They are closely related to cockroaches and can be regarded as one of the ancient ancestors of the insect kingdom, while ants are relatively closely related to bees. There are still far differences between the two in terms of morphology, evolution, and feeding habits. Compared with the age of human beings, termites are the oldest creators of social life, and they are called the originator of camp life.