Farming mushrooms is very different from farming nearly any other kind of food because, of
course, mushrooms aren't plants or animals. The act of growing mushrooms looks and feels
much more like growing bacteria in a lab. Fungi aren't bacteria either, they're their
own kingdom of life. But the bacteria analogy holds in as much as a mushroom farm is much
more laboratory than it is field. There is no field because mushrooms don't need light,
at least not in the same way that plants do. They aren't photosynthesizing anything, they're
not vegetables. Certainly lots of different kinds of mushrooms are cultivated lots of
different ways by lots of different people. I'm just showing you one example today, Middle
Georgia Mushroom in Macon, Georgia. Hunter Pruett, his grandmother, and his girlfriend,
Anna, grow mostly oyster and lion's mane mushrooms for local restaurants.
"We're bringing fresh gourmet mushrooms to Middle Georgia."
First step is to prepare a substrate — that is the substance on which the fungus will
both grow and feed. It lives inside its food, ain't that the dream? In the wild, mushrooms
can grow in the ground, specifically ground that has lots of biological material in it,
like old dead leaves. Or they can grow on dead trees, decaying wood. Hunter replicates
the dead wood substrate by using sawdust pellets. These are usually a by-product of sawmills.
People use them as fuel for grills and smokers, even home heating stoves.
"Once this stuff is hydrated, it turns into just the mushroom's paradise. Mushrooms in
the wild grow on hardwood species, so we found out that these pellets work just as good as
that."
Hardwoods are basically the trees that aren't pine-type trees. Conifers have that sticky
Christmas-smelling a resin in them, which has anti-fungal properties. For that same
reason, people don't usually cook with softwoods, they burn really dirty. You end up with food
that's coated in this kind of bitter soot. So, generally speaking, wood that is good
for cooking can also be good mushroom substrate.
"And what this is is we've taken those pellets, we've put them in that bag, and we've put
in a certain amount of water. We let that water absorb in that pellet and it comes out
to this nice little block."
The problem, of course, is that block is probably full of a rando microorganisms — microorganisms
that could grow in the very favorable conditions of Hunter's mushroom fruiting chamber, so...
"We bring it over and we put it in this big old barrel. We call this our atmospheric steam
sterilizer."
It's basically a big tank with a heating element at the bottom. Hunter loads the sealed bags
in there and pasteurizes them at 204 Fahrenheit, 95 C for 18 hours.
"What we're doing is just running steam up through the blocks. And it's just heating
that block up to 200 degrees, which is going to kill all that competition, those competitive
organisms."
The bags come out totally sterile. And then it's time to inoculate them with the fungus
that you actually do want to grow in there. From here on out, everything has to be done
in an ultra-sterile environment. The air is full of yeasts and molds and bacteria and
other things that could out-compete Hunter's mushrooms in that substrate.
"So there's one mold that mushroom growers are just fighting every day, and that's Trichoderma.
It's a green mold, it's your common mold that you find on breads. It loves to eat the same
kind of substrates as mushrooms."
So everything he does now, he will do while standing in front of this flow hood.
"What this does is it pulls air from the back, pushes air forward, and then pushes through
this HEPA filter."
Those jars, he's sterilized in a pressure cooker, everything else he's going to spray
with isopropyl alcohol cut with water, a 70% solution so it doesn't mean evaporate too
fast.
"Spray your hands down, spray your surface, spray your bag."
Here's what Hunter is starting from today: some mushroom culture that he has ordered.
You can grow mushrooms from their spores — their seeds — or you can grow them from mycelium
cultures, and the latter is generally regarded as the more reliable method. The mycelium
is the main body of the fungus, these white filaments that grow inside the substrate.
In that syringe, he has little bits of mycelium floating around in a sugar-water solution
that the mycelium can eat. And he's injecting it into jars with even more sugar water.
"It's a one-to-four ratio of water and light corn syrup. So the mycelium actually grows
on the sugars that are in the syrup. Go in the jar, we'll do about two and a half milliliters."
What he's doing here is expanding the culture that he's ordered — putting it in an environment
where it can rapidly grow so that he'll have lots more of it, and so it will last until
he needs it. The other advantage of liquid culture is that the mycelium won't grow a
mushroom in there, it has no structure to hold on to.
"We have a little stir bar. And what that stir bar is, is just a magnet. We put it on
the stir plate, and what that is, it's going to break that mycelium up, that way it can
spread throughout the jar."
That magnet spin — super cool way to stir something without potentially contaminating
it.
"Within seven to 14 days, this jar is going to be fully colonized, similar to this."
That's the thing about growing fungus instead of plants, everything happens way faster.
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Hunter can seed another jar with liquid culture, he's got to sterilize the needle, he's got
to work clean.
"We're going to turn our heat off, keep it in front of that hood, let it cool down. Squirt
a little out, cool it off, bring it in."
Now, before Hunter can grow mushrooms from his liquid cultures, he needs to test them
first. And he does that on Petri dishes, little plates covered with agar agar.
"Call me Agar."
If there are contaminants in the culture, they will present themselves as much more
readily in the Petri dish, they'll be able to grow. And the mycelium can actually grow
into a full-fledged fungus in there. So he's also looking to find particularly strong genetic
specimens — groups of my mycelium that are so good at growing and being alive that they
are out-competing other groups.
"And you can see how there's no synchronization with this mycelium, there's just groups growing
everywhere, right? So what we do is we would find a very healthy-looking group, like some
of this rhizomorphic here, some of the edge of this. And we'd cut it and we'd transfer
it to another dish. That way we can grow that good, strong isolation that we all hunt after.
So if you can get one good genetic growing, you can multiply that genetic tenfold. And
then that can be your genetic on your farm that you know how it grows in a certain temperature,
how long it takes to fruit, how long it colonizes — you know everything about that thing."
In contrast, look at this one. You can see that's not several different fungi all battling
it out, that's one coherent organism that Hunter has successfully isolated. You can
also clone a fungus you like by just chopping off a piece of the fruiting body, the actual
mushroom there, and putting it in agar. Hunter does that too. Here's a clone of a lion's
mane mushroom that actually started growing a new fruiting body inside the dish.
"It's actually just a suffocating fruiting body. You can see that it's coming out and
it's reaching for oxygen. So mushrooms are just like — they actually inhale oxygen
and produce CO2. So they're closely related to us humans. And he's looking for some oxygen,
that's why he's stretching out like that."
As we've discussed previously, fungi are actually closer to animals than they are to plants.
I have a whole video about what exactly mushrooms are, it's linked in the description. Next
step is for Hunter to use the genetic specimens he's isolated to inoculate jars of grain.
Those are literally just whole grain oats in there. Pretty much any kind of seed works.
Fungi like seeds basically for the same reason that you and I do: they're nutritious. Again,
he's just expanding his culture, growing more of it, and making sure it's pure, that it
hasn't been contaminated by some bread mold or something.
"Everything's white, there is no different greens and blues and pinks."
The other great thing about starting your mycelium in grain is that it's granular. And
you now have lots and lots of tiny little bits of things that are individually seeded
with your fungus.
"The thing important to farmers is how many different vehicles of inoculation you have.
You have probably, I don't know, 5,000, 6,000 kernels in this jar. And it's going to get
mixed into a big old bag of saw dust, and that grain is going to be distributed through
that saw dust."
So the grain spawn — that's what that's called — the grain spawn goes into the sterilized
bags of wood pellets, and he lets the mycelium grow in there for a week or two.
"You can see this thing is fully colonized, ready to go. And then you'll just get you
a sharp object and you'll slit that bag right there. And from here, she'll go into the chamber.
We'll place that block up and somewhere around 14 days she'll be fruiting some oysters."
That fruiting chamber is where the mycelium will grow an actual mushroom that'll come
up out of that slit in the bag. First they come out as little dots like that, those are
called pins or pinheads. About a day later, they might look like that. Then it's off to
the races.
"This'll be about that size tomorrow and then it'll come in and it'll be about that size
on day three, they are insanely fast growers."
And over that time, Hunter has to watch his fruiting bodies and manipulate the environment
of his fruiting chamber accordingly.
"So mushrooms in the beginning stages like very high humidity. Whereas mushrooms throughout
their life, as they start pinning, require much more lower humidity."
You can see this for yourself out in your lawn. It rains and then you see a bunch of
mushrooms sprout when it's really humid. And then if the air doesn't clear, if it stays
really wet or if it stays really stagnant, those mushrooms will rot really, really fast.
Alternatively, if things get too hot and too dry, the mushrooms just shrivel up, they're
like 90% water. So in general, they like really humid, somewhat dim conditions. That doesn't
mean they don't like sun light. Some mushroom species use light as a signal or a trigger
for growth. The precise reasons and mechanism for this are things that are still being worked
out by science.
"What we found, and I believe this is probably debatable, is that mushrooms actually use
sunlight as just a sense of direction that draws them towards oxygen. So if you think
that with all natural light occurring, the sun being the highest point, the organism
knowing that, they say, if I can get to the sun, then I can reach the oxygen."
Once the mushroom cluster is full grown, he's got to cut it off the block right away. The
mushroom is the fungus' temporary reproductive appendage. Its job is to grow up tall really
fast, cast the spores into the wind, and then just die back.
"So you really got to pay attention to them because if you let them get to a certain point,
when that cap starts to open up and those spores start to drop, this room is going to
be a mess, man. Your fans are going to get clogged up and your humidifier will get all
nasty."
The lion's mane mushroom drops its spores from those little teeth. And you can tell
it's ready when they get long — long in the tooth.
"This one right here is past its harvest prime. But I love the way this thing looks, man.
It's still totally edible. So you can really see that this mushroom has this stringy, crab-like,
barbecue-pulled-pork-like texture."
Once Hunter harvests the fruit cluster, he can grow another one from the same block — that's
called a flush. He can generally get three flushes from a block. Though they get progressively
smaller and more susceptible to contamination from a rando mold floating by.
"The nutrients start to disperse in the block, so it doesn't have a lot of food. The army
becomes weaker, right?
Can you tell Hunter is a veteran — all the combat metaphors?
"When the army becomes weaker and a new fresh contamination comes in, that contamination
a lot of times is going to win. It's going to take over that block and it's going to
be able to make its little stronghold."
At that point, the block goes in the compost and the whole process starts again. He sells
these inoculated blocks on his website, it's a kit that you can grow at home. I did that.
There's a link in the description. A common trait that I've noticed among mushroom growers
is they tend to be evangelists, they believe in the power of fungus — its power to be
a medicine, its power to be a sustainable protein source, even its power to filter pollutants
out of the environment.
"We want to turn this into a community thing, we want it to be a farm. We want this to expand
into some land and to really grow the awareness for fungus right in our community."
Might sound grandiose, but I don't think it is. That lion's mane, for example, has been
shown in mice studies to promote neurogenesis, the growth of new brain or other nerve cells.
Hell, it even looks like a brain. And it's been shown to improve cognitive function in
geriatric mice. Maybe it'll improve cognition in a geriatric me in a few decades, we'll
see. In the meantime, I'ma keep eating them, thanks to the hard work of laboratory farmers
like the folks at Middle Georgia Mushroom. Go get you some.