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Mycelium Running: How Mushrooms Can Help Save the World - A Book Review
ISSUE:
Page:
50-57

Scanning electron micrograph of primordial mushroom forming from a mycelial mat. 400X magnification. Photo credit Paul Stamets All photos courtesy of Ten Speed Press ©2007

by Solomon P. Wasser, PhD

Editor’s note: This article is an extensive review of the recent book Mycelium Running: How Mushrooms Can Help Save the World by Paul Stamets.1 This review was originally published in the International Journal of Medicinal Mushrooms2 and reprinted by kind permission of the author. This version has been condensed, edited, and supplemented with photos from the book.

Mushrooms represent a biologically and taxonomically distinctive group that provokes scientific and practical interest, due to their exclusive nutritional and medicinal properties. The number of mushrooms on Earth is estimated at 140,000, of which perhaps only 10% (approximately 14,000 named species) are known. Edible higher Basidiomycetes are acknowledged for their nutritional value and acceptability, as well as their pharmacological properties. They make up a vast, largely untapped source of powerful new pharmaceutical products. A novel application of mushrooms is using them to heal and improve the health of the environment, the so-called mycorestoration processes that are precisely described in Mycelium Running.

It is a great pleasure for me to review this book, which actually appears as a natural sequel to Paul Stamets’ Growing Gourmet and Medicinal Mushrooms,3 which I also had the honor to review previously.4 However, in Mycelium Running the author emphasizes mushrooms’ important role in “saving the world” in terms of mycorestoration—“the use of fungi to repair or restore the weakened immune systems of the environments.” Basically, this book is designed to show readers how to grow mushrooms in gardens, yards, and woods for the purpose of reaping both personal and planetary rewards. Of course, there is more said about the benefits that fungi provide to plants, animals, and humans, all of which I will summarize in this review.

Summary of the Book

This book consists of 3 basic parts, each one devoted to a different area of the fungal world and diversity, but still tightly connected to one another by the importance of fungi in nature and for humans, as well as in their current application in medicine and economics. There are 14 chapters with a total of 339 pages, including 360 high-quality color photos, a glossary, and an index.

Termitomyces robustus, a delicious edible mushroom, sprouts from an aged, abandoned termite colony. Photo credit Satit Thaithatgoon

Part I, “The Mycelial Mind,” has 4 chapters, all of which point to mushrooms as an integral part of natural ecosystems due to their continuously spreading mycelial networks and ability to grow in variable habitats. Mushrooms are the fruit of mycelia, which are the cobweb-like cell structures that constitute the vegetative part of fungi, usually found in underground networks. Fungal mycelia play an exceptional role in the steerage of nature by unlocking nutrient sources stored in plants and other organisms, building soils, and cycling nutrients through the food chain. However, because humans continually take advantage of all natural sources, they have become the main threat to their own survival. Fungi appear as “environmental guardians,” and as such should be treated responsibly, not just to save the environment but also to save ourselves.

In Chapter 1, “Mycelium as Nature’s Internet,” the author gives new insight into the fungal mycelia as biological and informational systems connecting the environment and its constituents together, thus representing a significant natural network. It might be compared with the modern Internet system, which connects people all over the world, giving a variety of information. Therefore, author Stamets calls the mycelial network “the Earth’s natural internet,” through which humans are able to communicate with the natural environment. Moreover, this network is considered to possess a sense for all the influences of the surrounding world, such as human footsteps, falling branches, etc. According to this idea, the author raises the possibility that another science could arise, dedicated to programming myconeurological networks in order to monitor and respond to threats to the environments: “Mycelial webs could be used as information platforms for mycoengineered ecosystems.”

The basic aim of Chapter 1 is to demonstrate the great importance of fungal mycelia for the web of life due to their ability to recycle plant debris, filter microbes, and restore soil. Today, humans use fungi and their biologically active compounds for destroying toxic wastes and for treating various diseases, including cancer. There is no doubt that all natural habitats need fungi for their survival, without which “the life-support system of the Earth would soon collapse.” Therefore, the basic moral of this chapter is that people should live in harmony with their natural environment instead of destroying it with toxic waste. Only by living in balance with their host environment will humanity create the opportunity to ensure the wellbeing of this planet.

Chapter 2 is dedicated to the biology of mushrooms, their life cycle, basic structures, and ways of growth and reproduction. According to how they form primordia (organisms in their earliest recognizable stage of development), mushrooms are divided into two categories, predeterminant and indeterminant. Most mushrooms are predeterminant, i.e., they form all the basic structures in the primordial stage. There are a variety of forms in which mushrooms can be seen in nature. Some of them are hoof-shaped; others are ridge-formed, cup-formed, coral-like, ear-like, etc. However, all of them produce spores in a similar way, although the terms and ways of spore release also vary. With spores, mushrooms can pass great distances, thus reproducing and reaching new habitats. For spore distribution, many animals and insects also play an essential role through eating or just carrying them. The author notes that mushroom spores and tissues can germinate in sterile laboratory conditions, thus giving a chance to produce new cultures in order to examine or to cultivate them. However, there is a slight difference between cultures created from spores and those created from tissues. Germinating spores can cause the expression of new phenotypes from the genome of the mushroom, but using a piece of living tissue just makes a clone of the same mushroom.

Bigleaf maples (Acer macrophyllum) grow in the rain forest of the Olympic Mountains in Washington State. Research by Cobb et al (2001) showed that this maple extends roots on its outer trunk that climb into the canopy, essentially creating a biosphere high above the forest floor. The biomass of these aerial roots is similar to the biomass of the subterranean roots. Upon these aerial roots, a complex habitat has evolved, including mosses (Nonvascular epiphytes) and licorice ferns (Polypodium glycyrrhiza; a vascular epiphyte), once thought to be parasitic to the tree but now known to be part of the tree’s healthy ecosystem. Photo credit Paul Stamets

Chapter 3, “Mushrooms in Their Natural Habitats,” describes the types of mushrooms, which are divided into 4 categories according to their way of feeding. Among fungi, there are saprophytes, parasites, mycorrhizal, and endophytes, although some exceptions also exist. All fungi, no matter which category, play a significant role for the diversity and welfare of ecosystems. For instance, saprophytic mushrooms are the basic decomposers of organic matter, supplying nutrients for plants, insects, and all living organisms. This chapter provides detailed information about the saprophytic subtypes and their specific characteristics as a separate category. Although parasites are considered blights, they also have a positive role in the reparation of damaged habitats.

However, the most interesting part of this chapter is dedicated to the mycorrhizal mushrooms, which live in a mutually beneficial relationship with plants and trees. Several mycorrhizae subtypes are described, but the most amazing discovery is that through the mycorrhizae, fungi transport nutrients to different species of trees. This knowledge supports the realization that “forests’ vitality is directly related to the presence, abundance, and variety of mycelial associates.” Unfortunately, it appears that mycorrhizal mushrooms are difficult, even impossible, to cultivate in laboratory conditions due to their dependency on a symbiotic partner as well as requirements for calcareous (limestone) soil and microorganism existence.

Mushrooms are able to live in symbiosis not only with plants but also with insects, snails, and slugs. For example, all the species of genus Termitomyces (Agaricaceae) live associated with terrestrial termite colonies, and some insects use certain mushrooms (Lepiota spp., Agaricaceae) to cope with bacterial or fungal infections. This chapter demonstrates that through all fungal allies (mycorrhizal, saprophytic, and endophytic), plants can survive starvation, dehydration, and parasitization. The author believes that fungi evolved throughout the centuries to support nature, protecting generations of organisms, and he appeals to the reader to honor this ancient mycological wisdom.

Chapter 4, “The Medicinal Mushroom Forest,” describes the diversity and huge importance of fungi in nature, as well as for humankind, in terms of natural bioactive compound producers. All the trophic groups of fungi (saprotrophes, parasites, mycorrhizal, and endophytic), work in concert in the ecosystems, thus governing the transition from living to dead matter. The variability of mushrooms in the forest is indescribable and valuable; however, many mushrooms, mainly mycorrhizal ones, are gathered for food due to their excellent nutritional properties. The most commonly collected mushrooms in North America are chanterelles (Cantharellus cibarius, Cantharellaceae), matsutake (Tricholoma magnivelare, Tricholomataceae), and hedgehogs (Hericium spp., Hericiaceae). Moreover, fungi as a whole represent a huge natural source of pharmaceuticals. There are numerous types of drugs originating from fungi (e.g., antitumor, cholesterol-lowering, antifungal, antiviral, and antibacterial drugs), mainly antibiotics such as penicillin, calvacin, campestrin, corolin, ganomycin, and agaricin. This is how the old forests, rich with a variety of fungal species, suddenly became, in the author’s words, a “remedy against natural or weaponized diseases.”

Because mushrooms and humans are somewhat evolutionarily close (fungal DNA is more closely related to animal DNA than it is to plant DNA), they share a common risk of infection by the same microbes. The author believes that each mushroom species predetermines which bacteria can live upon it. Therefore, the investigation of the interrelationships between mushrooms and their related bacteria, viruses, and bacteriophages can reveal new drugs for medicine. This chapter contains detailed information about mushrooms healing viral diseases with many examples and references on the subject. There is also a table representing the most explored mushrooms in the treatment of various viral infections, including HIV, as well as describing the mushrooms that show anti-HIV activity.

Mycorestoration, Part II of the book, focuses on the significant role of fungi in the restoration of damaged environments. Saprotrophic, endophytic, mycorrhizal, or even parasitic fungi can be used in mycorestoration. The author carefully presents this process to demonstrate the range of opportunities that mushrooms provide for healing in nature. Mycorestoration can be performed in 4 different ways: mycofiltration (using fungi to filter water), mycoforestry (using fungi to restore forests), mycoremediation (using fungi to eliminate toxic waste), and mycopesticides (using fungi to control insect pests). These methods represent the potential to create the perfect ecosystem, where no damage will be left after fungal implementation, even if there are some toxic wastes.

In Chapter 5, the author explains how the idea for mycofiltration first appeared and has developed throughout the years. Fungal mycelia can serve as filters of different substances, e.g., ink, water, and tobacco smoke; their filtering properties can be compared with those of cotton. Thus, the idea of “running” mycelium for cleaning the environment is born. Stamets shares his own experience from a trial of filtering spring water near his property where he introduces a mycelial bed of Stropharia rugosoannulata. Other mushrooms, e.g., oyster mushrooms (Pleurotus spp., Pleurotaceae) and wood conks (Ganoderma spp., Ganodermataceae), can also be used as microbiological filters. Mushroom mycelium can also filter some microbial pathogens, allowing the mycelia to be used for targeting bacteria and protozoa in a habitat. Interestingly, the pathogens passing through mycelial nets are digested by the fungi. However, if the fungal enzymes do not kill the pathogens, some of them are at least blocked from reproducing. A table is given representing mushroom species with specific antimicrobial effects on animal and human pathogens. Mycofiltration is a useful method for cleaning the water around animal farms, where a lot of organic waste can be found.

In Chapter 6 the author claims that without fungi there would be no forests. He explains the importance of fungi for forest preservation, recovery, and strengthening in terms of a single process, mycoforestry. Mushrooms play an essential role in nature’s life cycle by building soils, feeding plants and trees, influencing bacteria composition of the same habitat, contributing to the mineral compound cycle, etc. The author’s experience as a logger gives him a unique perspective regarding forestry life, as well as for the safety and wellbeing of forests. Mycoforestry is a newly emerging science with emphasis on the beneficial role of fungi for the forests. Stamets provides guiding principles for mycoforestry to steer research and development of new strategies. These principles include the use of native species in restoring habitats, selection of species that are known to be helpful for plant communities, selection of species according to their interactions with bacteria and plants, etc. He shows that mushroom species that share mycorrhizae with the largest number of host trees have the greatest mycoforestry potential, although only a few of them are commercialized as mycorrhizal spore inocula due to many obstacles. A list of these mushrooms is presented, along with the type of mycorrhizae and the preferred host trees. However, Stamets believes that despite all the obstacles, influencing the predominance of the selected mushroom species will help balance biodiversity. He gives an example of mycoforestry strategy applied during his research project in a half-cut old forest of Douglas fir (Pseudotsuga menziesii, Pinaceae), hemlock (Tsuga spp., Pinaceae), and western red cedar (Thuja plicata, Cupressaceae). Mushrooms appear also as an appropriate source for preventing forest fires if myceliated wood chips are spread along the forest floor, thus retaining water and lessening fire danger.

Environmental pollution with toxins, which are currently generated in huge amounts, is one of the main threats to nature as well as to humans. In Chapter 7, the author explains how mushrooms can be used successfully in the degradation or removal of toxins from the environment by employing the process of mycoremediation. Mycoremediation also includes the removal of heavy metals from the ground by channeling these toxins from the mycelia to the mushrooms’ fruiting bodies. Based on the enzymes that digest the wood cellulose and lignin, fungi are divided into two basic groups: brown-rot and white-rot fungi, although there are some species that produce both types of rot. Both brown- and whiterot fungi are good mycoremediators because of the enzymes they produce and their ability to degrade basic atomic bonds in a variety of toxins. Using fungi in nature in the decontamination of toxins includes many other organisms such as bacteria, insects, plants, fungi, and vertebrates, which are correlated to fungi directly or indirectly, thus establishing a multi-kingdom approach. One of the best mycoremediators is the mushroom Pleurotus ostreatus, which is known to possess a very high degradative capacity. Because most of the contaminated habitats contain both toxins and heavy metals, mycoremediation can be used in the revitalization of such places. Fungi are able to enhance their enzyme production when exposed to highly polluted conditions. Moreover, fungal mycelia destroy toxins even before they enter the food chain. A table matching some of the known toxin-absorbing mushrooms with the exact type of toxin that each one acts upon is included. Interestingly, many toxin-degrading mushrooms are being recommended to patients in order to break down toxin wastes in the human body.

Stamets also describes a long-term strategy of using mushrooms for neutralizing heavy metals, based on experience from the huge pollution from the Chernobyl nuclear plant damage. He appeals to all mushroom hunters who live in toxin-polluted areas to be extremely careful and not to collect mushrooms for food. In order to educate, advise, and warn the reader, the author has devoted a whole part of this chapter to the bioaccumulation of different heavy metals by mushroom mycelia and fruit bodies. There is a table containing the known species that are hyper-accumulators of arsenic, cadmium, cesium, lead, mercury, or copper. However, he points to the fact that because mycoremediation is still a young technology, many trials have to be conducted before its commercialization and thus, more precise methods will be discovered.

In Chapter 8, Mycopesticides, the author relates an interesting personal story about how and which fungi he uses to get rid of some carpenter ants that were destroying his house, and he provides some general information about fungi parasitizing on insects. Using entomopathogenic fungi, in the form of mycelium, against damage-causing insects is a natural technology that is also useful for controlling insects in such a way that is not harmful to the environment.

Part III, the heart of this book, describes the practical methods of mushroom inoculation, cultivation, gardening, and mushrooms’ nutritional properties. Stamets explains how to overcome the hurdles of choosing strains, getting mushroom cultures, etc. The myco-motto of mushroom growers is “Move it or lose it!” Chapter 9 describes methods for inoculating mycelium by using spores, spawn, or stem butts, although the author prefers to combine all these techniques because as he says, “the best method for generating mycelium is the one that works.” For example, to produce a new mycelium using spores, the simplest method is just to take a spore print, which he lovingly describes as an art of nature that is also essential for mushroom identification. However, he states that identification of mushrooms by spores alone is very difficult unless their DNA is analyzed. Several books are cited as field guides for mushroom identification by spore color as a primary distinguishing feature. Spore powder can be collected most easily on paper, but also by using a pane of glass or a plastic bag. Each mushroom produces a huge number of spores, e.g., the oyster mushroom, which converts 50% of its biomass into spores. Moreover, there are species like Ganoderma applanatum, which produces 5 trillion spores annually.

Stamets gives some helpful and detailed strategies for spore germination, such as using nutrified water, liquid spore-mass slurry, oils, cardboard, straw, and burlap. Because the mycorrhizal mushrooms are almost impossible to grow in culture, the author concludes, “this book concentrates on the easier-to-grow decomposers,” which are the saprotrophes. Further on in this chapter there are several methods for outdoor mushroom cultivation using cardboard spawn and stem butt spawn, and methods for making both cardboard and dowel spawn from stem butts. But how does one choose which mushroom stem butts to regrow? According to Stamets, every saprophyte with rhizomorphs is likely to be regrown using stem butts. However, he encourages experimentation with the stems of likely and unlikely mushrooms. Surprisingly for some scientists, it appears that some mycorrhizal species can also be transferred to new habitats using stem butts, which, however, must be placed directly into the rhizosphere of a young tree or plant host.

Chapters 10 and 11 are devoted to mushroom cultivation methods as well as some of the basic substrates used for this purpose. For example, straw can be treated using different methods in order for mushrooms to grow on it, although the methods described here are useful mainly for small-scale cultivators, people who live in rural regions, and those who are interested in less expensive techniques. Methods are described in detail for cold incubation of mycelium, hydrogen peroxide treatment, and heat pasteurization. Also provided are some methods as well as combinations of methods for how to inoculate mycelium on stumps.

Chapter 12 reveals the role of mushrooms in gardening, and Stamets notes that all gardeners are mushroom growers even though some of them do not know it. Using fungi in the garden increases yields, reduces the need for fertilizers, and builds soil structure for long-term use. Mushrooms provide a balance between the input and output of nutrients in nature.

Chapter 13 is devoted to the nutritional properties of mushrooms, which make them “healthy foods,” along with their medicinal properties. Helpful information is given about species that are known to be aromatase and 5-alpha-reductase inhibitors, which are thus promising agents to be used in the prevention of breast and prostate cancers. As for the culinary application of mushrooms, it is amazing to learn that there are mushroom-infused beers and wines, mushroom cookies and chocolates, and even mushroom ice cream!

Chapter 14 represents a catalogue of mushrooms that can be cultivated outdoors; all have scientifically demonstrated nutritional and medicinal properties. All species are described in detail with common names, taxonomic information, and descriptions of the fruit bodies and habitat as well as their distribution. There is also information about the natural methods of cultivation, nutritional and medicinal properties, and the potential of these mushrooms for mycorestoration.

Conclusions

In this reviewer’s opinion, Mycelium Running describes essential information about the mushroom world and includes many beautiful photos, amusing stories, and outcomes. First, this book is an excellent source of information for everyone who is or wants to be a mushroom grower. The book provides a variety of different methods and strategies for growing mushrooms using spores or mycelia without harming nature. The author encourages the reader to use mushrooms and fungi for outdoor cultivation and gardening. This book shows the importance of integrating saprophytic, mycorrhizal, and endophytic fungi. Rapid growth in mushroom technology requires constant updating of information.

Mycelium Running also describes how fungi can be employed to restore the health of the Earth’s natural environment, a concept the author calls mycorestoration. The book dedicates 4 chapters that explain these ecological methods: mycofiltration, mycoforestry, mycoremediation, and mycopesticides.

This book is written in a very accessible style, which makes it suitable for students, teachers, scientists, bioremediators, ecoforesters, physicians, futurists, professional and amateur mushroom growers, and anyone who is passionate about mushrooms. Professional mycologist will be inspired when reading this book. Mushroom growers will enjoy reading new ideas. And finally, the primarily curious will be encouraged to become either a mycologist or a mushroom grower. This book is recommended not only to the specialists, but also to anyone who is eager to learn more about the intriguing world of mushrooms.

Solomon P. Wasser, PhD, is head of the International Center of Biotechnology and Biodiversity of Fungi at the Institute of Evolution, University of Haifa in Haifa, Israel. He is also Scientific Adviser of the Department of Cryptogamic Plants and Fungi at the N. G. Kholodny Institute of Botany of the National Academy of Sciences of Ukraine in Kiev, and editor of the International Journal of Medicinal Mushrooms. Contact: spwasser@research.haifa.ac.il.

References
  1. Stamets P. Mycelium Running: How Mushrooms Can Help Save the World. Berkeley, CA: Ten Speed Press; 2005.
  2. Wasser S. A Book Review: Mycelium Running: How Mushrooms Can Help Save the World. Int J Med Mushr. 2006;8:1-10.
  3. Stamets P. Growing Gourmet and Medicinal Mushrooms. Berekely, CA: Ten Speed Press; 1993.
  4. Wasser S. Growing gourmet and medicinal mushrooms [book review]. Int J Med Mushr. 2001;3:279-285.