Mycoremediation Handbook: A Grassroots Guide to Growing Mushrooms and Cleaning up Toxic Waste with Fungi
review by Jack Kittredge
The purpose of this book, Alex says in the foreword, is to inspire people to use natural organisms to clean up human waste of all sorts. Fungi are particularly well adapted to this task of decomposition, he asserts, and this book is to serve as a guide to how to use them for this function.
He starts off making sure we are aware of the vastness of the problem of waste. Hazardous wastes, those that can cause “substantial threats to our health and the environment” are produced at the rate of 400 million tons per year. That comes, he says, to about 13 tons per second! These come from common products like batteries, cosmetics, cleaning products, paints, pharmaceuticals, and electronics. The US has 200,000 “superfund sites” that are unusually high in hazardous waste, whose cleanup will cost an estimated $1.7 trillion over the next 30 years. The scale and expense of this problem and its current technological solution make it daunting. One of the major techniques now used in such clean-ups is bioremediation with bacteria and plants. Dorr asserts, however, that mycoremediation can serve this role far more successfully and economically. He displays a graph from Paul Stamet’s book “Mycellium Running” which seems to demonstrate this advantage.
The next part of the book is devoted to showing how fungi (mushrooms, yeasts, molds, and mycelia) can degrade and remediate metals, chemicals and microbes.
Metals – 53 of the 118 elements on the periodic table are considered heavy metals, many of which have toxic effects on human health and the environment. These metals cannot be reduced to something simpler, but they can be remediated in any of four ways.
• Mycosorption uses the fungal mycelium to bind up the heavy metals via an ion exchange mechanism and concentrate them in its polysaccharide cell wall, later to be chelated and reclaimed. This is particularly useful when the metal is contaminating waterways.
• Solubilization makes metals more soluble or immobile by producing organic acids and other compounds which form complexes with the metals. Solubilization is best practiced using mycorrhizal fungi in combination with plants on contaminated soil.
• Translocation accumulates metals into mycelial networks where they are channeled into fruiting bodies, nature’s way of eliminating them from the soil.
• Mycoaccumulation is similar to translocation, allowing accumulation of the metal into a mycellial network. Various ways of disposing of the accumulated metals are then brought into play.
Chemicals – Fungal ability to produce powerful enzymes is well known. Brown, White, and Soft rot fungi actively degrade trees, including cellulose and lignen, and various manmade highly toxic materials such as Polychlorinated Biphenyls (PCBs), DDT, Volatile Organic Compounds (VOCs) , and Polycyclic Aromatic Hydrocarbons (PAHs). Many complex chemicals are degraded to their constituent elemental ingredients, leaving harmless residues.
Microbes – Many common pathogens (bacteria, viruses, protozoans) are harmless, but a few cause food poisoning or deadly infections. Fungi are able to attack and kill many such pathogens (penicillin was one fungal product that started the whole industry of fungal antibiotics).
Much of the book is composed of lists of metals, chemicals, and microbes and which fungi can remediate them. These are listed both by pollutant and by fungi, for ease of finding by the reader.
Dorr discusses the practical details of mycoremediation projects, including needed bench scale tests before starting the whole project, and on-site pilot tests to find the practical realities you will encounter before undertaking the actual work.
The key to fungal usefulness in remediation is their ability to secrete enzymes. Some 4000 are recognized and a total of at least 25,000 are speculated to exist. Various ways to extract enzymes are provided, and a list of some 3 dozen types is given along with the species that produce them and their common uses.
A section on water – fresh and salt – pollution and remediation is interesting. One project which caught my interest was dealing with the amazing amount of floating plastic trash in our oceans. Dorr reports a plan to collect that trash (there are natural spots where ocean currents bring much of it together), expose it to ultraviolet light, and then degrade it with fungal enzymes.
The endophytic fungus Pestalotiopsis microspora, which can use polyurethane plastic as a primary food source either in the presence or absence of oxygen, is proposed as a way to manage our toxic landfills.
Of course any type of remediation is potentially dangerous as it deals with deadly substances and powerful enzymes, and Dorr cautions the reader about such dangers. A number of practical plans to help the amateur get started cultivating fungi seemed well thought-out. Inoculating cardboard and various substrates to get easy cultures, making a glove box for semi-sterile work, building a laminar flow hood for isolating your culture from contamination, making agar, preparing grain, making a spore print, and cloning mushrooms are among the practices suggested and shown.
For the young scientist, Dorr outlines a case study on fungal remediation that would make an ideal science project. It involves mycoremediation of cigarette butts, one of the most littered objects in the world. An estimated 1.7 billion pounds of them are disposed of per year, a huge amount of cellulose acetate plastic that can be broken down by appropriate microbes.
Dorr used Pleurotus ostrestus from a liquid culture, trained it on clean butts, then exposed it to dirty butts. Within a month it was colonizing the dirty butts, having developed the enzymes necessary to degrade them.
Dorr is not a scholar and this is not a scholarly book. It is a handbook for those who want to get involved with fungi as a means of cleaning up toxic waste. If that fascinates you, I can’t think of a better book to get started with.