Healthy trees need fungi

Chemist Dr. Helga Mölleken on the use of special forest and meadow inhabitants

They grow camouflaged or brightly in our forests, in open meadows or blood-red by the wayside. They can be used in gourmet dishes, as a remedy or to produce deadly poisons. We are talking about fungi. These weeks, their lovers and collectors can often be seen roaming the woods. Equipped with weatherproof clothing, a Bergisch Zöppken (a classic kitchen knife from Solingen) and a wicker basket laid out with a towel in which the often painstakingly found spore treasures are placed. Dr. Helga Mölleken, a chemist from Wuppertal, works with medicinal fungi as food supplements and with the composition of forest soils. She knows what a mycological creature (mycology is the science of fungi) needs to thrive.

Fungi in our woods

"September is when the real fungi season starts," she begins. "Although some fungi, such as the bovist, can also be found as early as August. Various types of fungi, such as the meadow mushurm, forest mushroom or the prairie mushroom, also start showing up in late summer." In Wuppertal's forests you can then find chestnuts or autumn trumpets. One has to be careful with the Schopftintling, which can only be used as an excellent edible mushroom when it is very young. And when its cap is still closed, but which melts into ink when left for a longer period of time. "But you can also find porcini mushrooms, chanterelles, Hallimasch and sheathed woodtuft," the scientist says.
Fungi often only grow in deciduous or fir forests. Mölleken explains: "Many trees only show healthy growth with the help of fungi, the mycorrhiza fungi. With their hyphae (fungal threads), they support the fine roots of the trees," she says. "The fungus spins its mycelium, a weave of fungal threads called mycorrhiza, around the root tips of the specific tree. With the help of these fine fungal threads, fungi can make better use of soil water and also absorb additional nutrients and minerals from the substrate." The fine branches of the mycelium can absorb these nutrients much better than the coarser tree roots and pass them on to the tree. In return, the tree supplies the fungus with carbohydrates that it cannot build itself.

Not all fungi can be cultivated

"Fungi are divided into different groups in terms of their nutrient uptake," the chemist explains. They are called saprobionts, parasites and symbionts, which open up different habitats. "The saprobionts decompose dead organic material such as leaves and deadwood. Also, these fungi decompose not only plants but any kind of living things like dead animals and other fungi."  Champignon and oyster mushrooms, on the other hand, are not very picky. They grow on dead leaves or deadwood in the forest, as well as in the basement, on straw bales, or horse manure. These fungi are therefore relatively easy to cultivate and are an important food factor. The situation is different with the well-known forest dwellers, whose living environment cannot be produced artificially. "The cultivation of chanterelles and porcini mushrooms, for example, has not yet been successful," she explains. "These fungi belong to the mycorrhizal fungi and live in symbiosis with trees."

Fungi are not unproblematic as food

Although experts consider fungi to be more important than fruit and vegetables due to their high vitamin B2, B3 and D content, Mölleken is critical of their use as food. "Vitamins are essential nutrients for our body and, with the exception of vitamin D, must be taken in through our food. I believe that a balanced and varied diet is crucial for our health." With regard to fungi, for example, the situation is still problematic in Bavaria. "After the Chernobyl reactor accident in 1986, forest fungi are still radioactive there, i.e. contaminated with radiocesium (caesium-137)." And to be able to understand what this means, she continues: "Eating 200 g of mushrooms with 3,000 becquerels of caesium-137 per kilogram results in an exposure of 0.008 millisieverts. This corresponds to the radiation exposure of a flight from Frankfurt to Gran Canaria." In addition, pollutants from industry and households are also found in the fungi fruiting bodies. "Some fungi even store heavy metals such as cadmium or mercury."

Medicinal fungi research is still a young science

Some fungi are not only very tasty, they are also said to have healing properties. A local example is the giant bovist, popularly known as the civil servant's cutlet, which can be fried in slices like a schnitzel. It can produce over seven trillion spores and also contains the anticancer agent calvacin. But how effective are medicinal fungi actually? "Medicinal fungi have been used in China in traditional Chinese medicine (TCM) for about 5,000 years," Mölleken knows. "Modern research on medicinal fungi, on the other hand, only began in Tokyo/Japan in about 1936 with the primary aim of collecting and critically analysing methods and experiences of traditional use. From older publications it is known that the mucoprotein calvicin is used as a natural remedy for various diseases such as bleeding or diarrhoea. Since about the beginning of 2000, there have been studies on the effect of calvicin on cancer cell cultures, such as lung or breast cancer, where cell growth was inhibited." However, more detailed studies are still needed for this, the scientist explains.One thing is clear: "In many Asian countries, fungi have long been used for health maintenance and healing. In Europe, too, they are becoming more and more widespread as valuable foods and in therapeutic applications. One example is the so-called beta-glucans in the fungal cell walls, which are also found in barley and oats. "For many decades, these have been the subject of numerous scientific studies. It is proven that they can help regulate blood sugar, improve the feeling of satiety, positively influence intestinal health, activate the immune system and lower blood cholesterol levels." Similar to the calvicin found in bovist, beta-glucans belong to the immune regulators, Mölleken knows. "They are also effectively used in TCM for the treatment of cancer, ulcers, infections, radiation exposure and trauma. But again, more intensive research is needed in human medicine." Next year, after her retirement, Mölleken will again be involved with this research topic in a planned research project.

The largest living creature in the world is a fungus

A very special fungus, the giant Hallimasch, whose small relatives can also be found in our forests, has even made it into the Guinness Book of Records. "The giant Hallimasch is a fungus of gigantic proportionsin Oregon, covering nine square kilometres, which is the equivalent of 1,200 football fields," says Mölleken. "The age of this Hallimasch is estimated to be around 2,400 years, making it one of the oldest living creatures in the world."And the natural scientist also has an answer to the final question on where the name Hallimasch actually comes from. "There are several versions of the German name Hallimasch for the mushroom Armillaria mellea. One of them derives the word from 'hell in the ass', as this fungus can have a strong laxative effect if eaten raw or insufficiently cooked."

Uwe Blass (Interview on August 24, 2021)

Dr. Helga Mölleken is a research associate at the Chair of Management of Chemical Processes in Industry and Analytical Chemistry at the University of Wuppertal.