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Please note: I’ll be updating this page in the next few weeks with better directions and photos…I promise!

Here’s an explantation of the mycoboom and directions on how to build one.

What is a mycoboom?
A mycoboom is a long burlap sack, filled with straw, inoculated with mushroom spawn. The mushroom spawn forms a weblike structure called mycelium within the straw that acts as a filter. When released in a body of water, the mycoboom will float on the surface and filter toxins out of the water, like E. coli, pesticides, fertilizers and heavy metals.

Who invented the mycoboom?
Mycologist (fungi scientist) Paul Stamets invented the mycoboom. You can read his explanation of the mycoboom here: (photos at the bottom). I met Paul when I was bicycling across the country filming a documentary about solutions to climate change. Paul explained to me about how cardboard boxes inoculated with fungi and tree seeds could grow forests Ever since then, I’ve been looking into Paul’s research—which I find both fascinating and inspiring. When I learned the IMA’s lake was polluted, I decided to try to apply Paul’s research on mycofiltration to help the lake.

How does a mycoboom work?
First, let me explain a few key words: Mycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. A mushroom is the fruit of a fungus. Paul refers to mycelium as a “grand recycler” and “nature’s internet” because mycelium absorbs nutrients from its environment, breaks down complicated nutrients into smaller building blocks for life, and transports them throughout the soil. Mycofiltration is the use of mycelium to filter water. A mycoboom is a type of mycofilter.

According to Paul’s book Mycelium Running, “Mycofiltration is the use of mycelium as a membrane for filtering out microorganisms, pollutants, and silt. Habitats infused with mycelium reduce downstream particulate flow, mitigate erosion, filter out bacteria and protozoa, and modulate water flow through the soil. More than a mile of threadlike mycelial cells can infuse a gram of soil. These fine filaments function as a cellular net that catches particles and, in some cases, digests them. As the substrate debris is digested, microcavities form and fill with air or water, providing buoyant, aerobic infrastructures with vast surface areas. Water runoff, rich in organic debris, percolates through the cellular mesh and is cleansed.” (pg 58)

When Paul built a mycofilter on his property to prevent the manure from his herd of black angus cows from polluting his downstream neighbor’s oyster farm, he found a hundred-fold drop in coliform levels. You can read more about this here:

How is a mycoboom made?
I’ve been building the mycobooms by reading Mycelium Running, the essays available on Paul’s website, and by asking employees at Fungi Perfecti (Paul’s company) questions. These are by no means perfect directions, but here’s what I came up with through my experimentation:

1. Sew burlap tubes. I sewed them 20ft long by 1 foot diameter. You can use the formula “circumfrence = π times diameter” to figure out how wide of fabric to buy. I ordered the burlap here: This burlap is untreated—meaning it isn’t dipped in diesel or copper sulfate. It comes in 40 inch wide yards, so I just cut it in 20 ft strips, folded it in half and sewed it one inch from the edge (I didn’t even pin it!) with polyester string. At either end, I put in a jute drawstring by sewing a one inch hem and threading the string in with a bodkin. Then, I flipped them inside out. I’ve also sewed a few mini-mycobooms 10ft by 6” diameter to see if the smaller size works better—they are definitely more maneuverable!

2. Pasteurize the straw. Pasteurization knocks out the competitor molds and fungi. This way, when mushroom spawn is added it will have a head start at colonizing the straw first. Paul explains a lot of ways to do this in Chapter 10 of Mycelium Running. The way I chose was pasteurization by submersion in hot water, which entails heating the straw in water to 160 degrees Fahrenheit for one hour. To do this, I bought a “High Power Gas Burner” from Fungi Perfecti:, a 55 gallon unused food grade drum from B & B Box and Drum in Indianapolis, organic straw from Central Indiana Organics, and a propane tank. Other materials I used were: matches, a tarp, a pitch fork, cinderblocks, stones, floating thermometer, 5 gallon bucket, and water. I was lucky enough to be able to collaborate with Rhett Reed on figuring out the pasteurization process, which made it easier and more fun! Many hands make light work! Rhett and I set the drum on the cinderblocks because the burner can’t hold the weight of a full drum. We used the bucket to put the lake water into the drum, turned the burner on, added a whole bale of straw, put stones on top to weigh the bale down, and turned down the burner when it got to 160. After 1 hour, we pitchforked the straw out of the barrel and spread it on the tarp. We made sure we didn’t go up to 190 degrees, because if we did a black or pink mold will appear in a couple days. After pasteurizing, we have 1 week to 10 days to use the straw before it gets contaminated again.

3. Pasteurize the burlap. Follow the directions above, just put in the burlap tubes rather than the straw. Other thoughts I’ve had about an easier way to sterilize the burlap would be washing and drying it in a household drier or putting it in a freezer for five days.

4. Stuff the mycobooms. The stuffing process is pretty simple. For every two or three handfuls
of straw I put in one or two handfuls of spawn. (A handful of straw is naturally bigger than a handful of spawn). I bought Pluerotus Ostreatus spawn from Fungi Perfecti. I bought their sawdust spawn and plug spawn, but in retrospect I think I should have used their grain spawn because it supposed to colonize more quickly and I think it maybe works better to inoculate straw (a grain) with a grain spawn. I calculated that I should use a half pound of sawdust spawn per square foot of straw and one plug per square foot. The amount for grain spawn is 10-20%. I was a bit confused on whether to pack the mycoboom really tightly or loosely. I ended up packing it loosely because I thought it would float better, but they are still sinking.

5. Water the mycobooms. Mycelium Running says that if you inoculate immediately after the straw cools from pasteurization and water them deeply each day, then they can be completely colonized in one week. For the mycomulch filter the directions are to water for 30 minutes with a sprinkler each day for the first two weeks to charge the filter. I adapted these directions to drench the mycobooms once a day (or twice a day if they are in the sun). I’ve been rolling mine into the lake water, but I think there would be less chance of contamination if I was closer to a spigot and could use tap water. So, ideally mycobooms should be built near a clean water source and in the shade. I’m giving mine a full week to colonize on the beach before I launch them into water and hooking them to the island.

Now, I will have to troubleshoot how to get them to float. I’ve put one into the water which has gotten waterlogged and is now slightly sinking. Maybe putting pieces of wood inside or strapping wood to the outside will help it float? Please let me know if you have ideas. I’d like to avoid using anything that isn’t biodegradable (like plastic or styrofoam). I didn’t forsee this would be a problem because of the photos I saw of the mycobooms at the bottom of Paul’s writing: