The Wonders of Mycelium — What is it and why is it so wonderful?
by Dr. Dennis Desjardin
Fungi shared a common ancestor with animals about 1.2 billion years ago when all life was unicellular. Around 750 million years ago, fungi developed multicellularity through a process where individual unicells did not disarticulate after development and instead formed chains of cells called hyphae. These hyphae grow and branch at their tips forming interconnected linear filaments a tenth the diameter of a human hair, collectively called mycelium. Nearly all of the life cycle of an individual fungus is spent as mycelium which can live for months to millennia. The mycelium is usually cryptic, performing myriad ecological roles in the biosphere. Under appropriate conditions this mycelium may form asexual spores, disarticulated cells used to clone itself, or it may fuse with mating compatible mycelium to form new structures capable of producing sexual spores, assuring genetic diversity in the offspring through assortment of alleles and genetic recombination during meiosis. Some lineages of fungi form macroscopic sexual structures commonly called mushrooms on which the sexual spores are formed and dispersed. Hence, mushrooms are just the short-lived, sexual reproductive phase of a fungus, produced by the long-lived mycelium phase which performs most of the vital ecological roles.
Because of their ancient shared history, fungi and animals share a number of metabolic processes, primarily that both lineages are heterotrophic, i.e. they cannot produce their own complex organic compounds for metabolic synthesis, but must ingest them. Animals do so with a gut. Fungi mycelium does this by producing a suite of extracellular enzymes that they exude into a substrate or host wherein they breakdown complex carbohydrates, proteins, lipids, alcohols, and other compounds into smaller fractions which are reabsorbed and further digested with endoenzymes into compounds needed by the fungus for growth and differentiation. The process of extracellular digestion is not 100% efficient; some of the breakdown products are not absorbed but are utilized by other organisms in the environment. In this regard fungi are altruistic.
There are an estimated 3 million species of fungi on our planet, 95% of which are currently unknown. This great diversity serve a number of critical roles in the ecosystem.
Saprotrophic fungi obtain their nutrition by decomposing dead organisms or inorganic compounds—the Great Recyclers releasing otherwise bound essential elements for use by themselves and other organisms. Biotrophic fungi obtain their nutrition by associating with living organisms, as pathogens, commensals or mutualistic symbionts such as mycorrhizae and lichens. The health of our ecosystems are dependent upon fungi, and in all cases, it is the mycelium or a unicellular yeast phase that serves these primary ecological roles. Whether a decomposer of dead leaves and wood, a pathogen of an agricultural crop, or a symbiont of the roots of forest trees or prairie grasses, the mycelium is the workhorse and there are myriad challenges it must overcome to be successful.
The mycelium must be efficient at recognizing and locating resources, achieved through hormonal control and regulating specific cell surface receptors. It must outcompete other organisms at utilizing its food source through optimizing faster growth rates, and better assimilation of nutritional components. The mycelium must avoid a host’s or competitor’s defenses by neutralizing inhibitory compounds, detoxifying poisons, or producing its own allelopathic compounds. Mycelium is tasty to predators so it must develop mechanisms to avoid them or reduce their impact, and heal wounds. Mycelium must adapt to changing local environmental conditions, avoid desiccation, neutralize adverse UV radiation, and regulate temperature and pH for optimal growth and differentiation. Over millions of years of evolution, fungi have developed various metabolic pathways for the production of unique compounds needed to overcome these challenges. Mycelium is wonderous, and by knowing the metabolic biology of specific fungi we can exploit them to serve our needs.
Edible (non-poisonous) mushrooms have been consumed as nutritious food for millennia. They are considered as a healthy food because they are rich in bioactive compounds including polysaccharides, dietary fibers, proteins, essential amino acids, vitamins, minerals, terpenoids, steroids, and adenosine derivatives [1,2]. Selected edible species, now called functional fungi, have been used medicinally because they produce compounds that have been shown in pre-clinical and clinical trials to have antioxidant, anti-inflammatory, anti-tumor, anti-aging, immunomodulatory, and glycemic regulation properties. In the last few decades, the mycelium stage of the mushroom life cycle has rightfully received greater attention as a source of nutrition and medically important bioactive compounds. Recall that mushrooms are produced by and formed from mycelium, and the two morphologically distinct but metabolically similar life forms produce the same suite of compounds but in varied concentrations, with a few exceptions. The debate whether mushrooms or mycelium provide more nutritional and medicinal value is disingenuous. It is apparent from the available published data that both mushrooms and mycelium produce compounds beneficial to health and wellness [3,4]. For a review of case studies of functional fungi addressing this topic, refer to my analysis online at https://semperaorganics.com/news/latest/mushrooms-versus-mycelium-a-misguided-debate-2/.
Consuming mycelium as food began in 1985 with the launch of Quornä by Marlow Foods in the UK. Formed from the filamentous mold Fusarium venenatum, it is high in protein (termed mycoprotein) and marketed as a meat substitute. Since then, numerous companies have developed mycelium of various molds and mushrooms into nutritious foods—for example, Meati Foods, Prime Roots, Better Meat Co., Enough Foods, MyForest Foods, Fable Foods and others. Our own company, Sempera Organics, produces MamuÒ made from mushrooms and mycelium of three species. The benefits of consuming mycelium include an excellent source of protein and dietary fiber, rich in B and D vitamins and minerals, low in fat, and contains no cholesterol or gluten.
Mycelium is also playing an increasing role in the nutraceutical industry as pre-clinical and clinical trials show the efficacy of mycelium from selected species in promoting health and wellness. As one example, a recent human clinical trial with full spectrum (mushroom and mycelium) organic Lion’s Mane blend (SO-DSX1, Sempera Organics Inc.) reported that Hericium erinaceus may improve the speed of cognitive tasks and reduce subjective stress in healthy young adults [5]. The mushrooms of this species contain hericenones, while the mycelium contains erinacines, two groups of compounds that promote NGF (nerve growth factor) and BDNF (brain-derived neurotrophic factor) synthesis. Additional trials are ongoing to study the effects of Lion’s Mane on enhancing cognition.
Mycelium is being used in the biological manufacturing of industrial materials, often using agricultural wastes as substrates. It is engineered to match the texture and strength of selected products and has properties that make it non-toxic and resistant to fire, water and mold contamination. Mycodesign and mycofabrication techniques have resulted in new products such as packaging, insulation, garments, and building materials. Mycelium is also being used in mycofiltration—wherein mycelium captures and removes contaminants from soil and water; mycoforestry—inoculating chipped woody debris with native saprotrophic fungi then distributed over recently cut forests to speed up decomposition, aid in soil formation, and increase forest ecosystem resilience; and mycoremediation—using mycelium to detoxify contaminated soil, decompose plastic, and remediate waste from roofing, asphalt and chemical manufacturing industries. These are just a few of the innovative ways to utilize the power of mycelium.
As we enjoy consuming mushrooms on our pizza, portabella burger, or thinly sliced over pasta, let’s not forget about the cryptic yet wonderous mycelium that supports and gives rise to the mushrooms we cherish.
1 Zhang Y et al. 2021. Healthy function and high valued utilization of edible fungi. Food Science and Human Wellness 10(4): 408–420.
2 Yu Q et el. 2020. Analysis of nutritional composition in 23 kinds of edible fungi. Journal of Food Quality Vol. 2020, Art. ID 8821315, 9 pg.
3 Berger RG, Bordewick S, Krahe N-K, Ersoy F. 2022. Mycelium versus fruiting bodies of edible fungi—a comparison of metabolites. Microorganisms 10(7): 1379–1395.
4 Cohen N, Cohen J, Asatiani MD, Varshney VK, Yu H-T et al. 2014. Chemical composition and nutritional and medicinal value of fruit bodies and submerged cultured mycelia of culinary-medicinal higher Basidiomycetes mushrooms. International Journal of Medicinal Mushrooms 16(3): 273–291.
5 Docherty S, Doughty FL, Smith EF. 2023. The acute and chronic effects of Lion’s Mane mushroom supplementation on cognitive function, stress and mood in young adults: a double-blind, parallel groups, pilot study. Nutrients 15(22): 4842. https://doi.org/10.3390/nu15224842