Making building materials with microbes

In the pursuit of growing a building, we ask if the microbial world is capable of giving us raw building materials...

Jonathan - My name is Jonathan Dessi-Olive. I'm an assistant professor at the University of North Carolina at Charlotte, and I teach courses on building structures and biomaterials. We have built buildings with the same materials for a really long time. And what we're starting to see is that while some of those materials have done us well, historically, they have lasted a very, very long time, nearing permanence. We're also starting to see that as we start to make composites, so as we start to bring multiple materials together, sometimes we bring them together in ways that are not reversible. And so what we're doing in my lab is looking at how we can start to partner with new materials. Materials that can be cultivated, materials that can be manufactured, but rather than using petroleum or high energy processes, we can use quiet, sustainable, organic growth.

Chris - What sorts of materials are these?

Jonathan - My particular focus with these sorts of new biological materials are the use of fungus, more specifically mycelium, which is the root part of the fungus. So under the ground, mostly invisible to us is a intertwined, interweaving network of these literal tendrils, and they weave together like a web and they, and they're the ones that are actually doing all of the work of the fungus under the ground. And so what we're trying to do is use that root structure of the fungus as basically a self forming glue. We get the fungus to start to grow. So we have wood chips, we introduce a mushroom, and then we grow that mushroom through those cellulosic fibres until we have a sort of solid mass. So the fungus is really acting as a glue to hold together these wood chips or these cellulose fibres.

Chris - What's doing the glueing though?

Jonathan - Oh, so the glueing is actually being done by the fungus. So the fungus, as it starts to cultivate, grows onto and through the cellulose. The cellulose is both.

Chris - So in other words, the fungus is almost like liquefying or releasing, liberating components of the thing it's growing through. But as it does so, they become sticky and bind together.

Jonathan - That's right. It binds together everything that it grows through.

Chris - And do this presumably to the extent the fungus gets as far as binding stuff together, but then you presumably have to stop the process before it degrades the material too far, because you're going to peak at some point in terms of strength and then the integrity is going to start to fall apart.

Jonathan - That's absolutely right. It's a very controlled process. So on the front end we have to be very conscious and very deliberate about the environment that we're providing for this fungus to grow. It needs warmth, it needs humidity, it needs proper access to its food. It needs a very, very clean environment that whole time. And mycelium itself, so these little root like fibers, they like it to be quite dark. On the other end of it, like you say, you have to stop the growth.

Otherwise it would deplete its food source and you would end up with a sort of gooey mess.

Chris - Presumably you got to kill the fungus.

Jonathan - Yeah, through heat. So for very small objects, we can put them into an oven. So a conventional oven, like you might find in your kitchen and at about 80 degrees Celsius, you can then put an object into that oven and essentially bake it dry. And that will, that will completely stop the growth of the fungus.

Chris - What sorts of things can you make with this?

Jonathan - We make all sorts of things. At the sort of product scale, one could imagine things like acoustical panels or cushions, or there's a company in Italy that is also making sort of floor tiles that resemble cork. At the big scale, we're thinking about growing buildings or at least building components. And in my lab, we've grown everything from just that, an acoustical panel all the way up to a small pavilion for a barbershop quartet.

Chris - Does this meet our aspiration? You started by saying that one of the big worries here with modern construction techniques is we've made some wonderful materials until the day you want to recycle them. Does this solve that problem? As in can we literally dismantle one of your pavilions and grind it up and scatter that to the four winds and it's made no impact on the earth whatsoever?

Jonathan - Well, that's certainly my hope. And I think that's what makes mycelium materials so exciting for me. When we talk about buildings and design though, we think that permanence is something that makes whatever that thing is important. And this material being something that, like you say, it could get just simply get dismantled is I think both really romantic and exciting.

Chris - Traditional building materials, we understand very well, as you pointed out earlier, we've been working with some of them for thousands of years, literally. So we understand their strengths, their weaknesses, and their constraints. What do the properties of these new materials look like? Are they any good?

Jonathan - From a structural standpoint, these are not stone. These are not brick. They're not concrete. They're not even wood. They resemble styrofoam to be quite honest. So they are good at certain things. What we are making with these materials is maybe not what they are best at. And I think that's what we as humans working with this biological partner now have to try to find out. And because it doesn't talk back, we just have to continue experimenting with where are they going to perform best in our lives?

Chris - The thing that's going to be the absolute arbiter in the future is going to be climate change in terms of whether we do something or not, because I think it's going to become harder and harder to convince people that something should happen if you can't say it's got good carbon credentials. So I get what you're saying that we have in the past viewed buildings as very much a permanent thing. And it's a success story if it's like the pyramids and still here 5,000 years later, and that this could be five minutes, but it's all going to come down to the energy equation, isn't it? So it sounds good, something that will last five minutes and then won't cause any pollution. But if it's caused a whole lot of carbon cost in making it, getting it to site, erecting it, then it's no better than if you had actually produced a whole lot of concrete.

Jonathan - The truth is that forever has shown historically to mean something more like 40, 50, 60 years. And so, yeah, there's those energy costs upfront, but then there's also maintenance costs over the lifetime of the building. And so those energy measures I think are going to be, well, they're increasingly complex because like you say, there's an immense amount of energy that would go into this at an industrial scale to keep an environment warm and humid and clean costs a lot to dry objects that are made of mycelium materials and dry them at large scale costs a lot. It doesn't actually cost as much, let's say as manufacturing insulation foam, the bottom line is going to be sustainability and how we can justify it. But in some cases, those measures may not be convincing enough, at least in the United States. There's certainly the perception that demolition is not only cheaper financially, but is just easier. And in some ways that's going to be a limit, whether or not it makes sense to demolish a building and put up another one and all of the energy associated with that. At some point we may just decide, well, that's not really what we want to do. For me, the limitation is less about, you know, can we do it? It's will we want to.