 Hi everyone, my name is Ej and I'm a grad student at the Department of Biological Engineering here So I worked with Professor Timothy Liu at the synthetic biology center as well as Neri here So I would like to thank the organizers. This is an amazing opportunity for us to like brainstorm the future of biological variables So today I'm going to talk about how we can actually grow These materials from kombucha cultures So I'm really happy. I'm not the first speakers of Rachel did an amazing job laying all the foundations because often times You need to convince people like why you need bugs in your materials. That's a phase So since we are now all on board living materials, they are very cool they can sense and respond to environment and this is due to like the huge advancement in the past two decades on Synthetic biology so we can actually program cells to sense compute record and actuate just like how you program computers So there are a lot of living materials kind of work that was proposed in the past ten years So there are different design space you can operate in them from so these are like the three most important Dimensions I think personally so you can have a micro scale Materials like biofilms and you can have macro scale materials like bricks and mycelium like mushroom walls Also, you can use the different design approaches. You can do a top-down So you pre-define the forms you 3d print it you do casting hydrogel devices or you can do bottom-up So you encode the information in a genome of the microbes so they can do morphogenesis and of course You can have artificial scaffold like what we have seen before or you can have the microbes produce the material like the matrix by themselves So the work I'm going to talk about is like at this corner where we use a bottom-up approach everything's encoded in the DNA and then it's at a macro scale and it's a biologically fabricated matrix So this work is in collaboration with the alleys lab and Imperial College London Because one day they came to us. They say hey, we found this really cool kombucha material and we isolated one bacterium from Czech Republic That's really like amazing in producing a lot of cellulose So we look into kombucha culture. We know this is like a hipster drink. It's very healthy for you as They say me personally I'm not going to make any scientific claims about that But you can grow this in your kitchen and the kombucha mother is a very strong material and Potentially they can live forever as long as you like transfer the mother into new batch of tea and sugar So of course a lot of artists they have done amazing work using this kind of material So apparently you can make clothes you can make one dressing and you can make a lot of different devices out of this Kind of bacterial cellulose materials So we were looking at different kind of like naturally occurring living materials The most obvious example is plants. So you see they can respond to light They can have different like functionalization on different surfaces on the tree leaves and they can react into Stimulate so like chemicals or like some molecules in the gas and also they have this symbiotic division of labor So most of the plants they actually coexist with microbes and they perform different texts So we were thinking like so in this Kombucha thing there are usually two members you have bacteria that produces cellulose and you have yeast that You have yeast that produce like basically alcohol and provide food for the bacteria So we were thinking this is like a pretty good analogy. So in a leaf You can see like different kind of specialist cells they per there are like in charge of different tasks But like in this cold culture we engineer we can actually have the bacterium produce the material and have the yeast To be the computer that do the sensing and then compute and then provide an output So this is the schematic We are not going to engineer the bacterium for like the first reason Biology is messy and slow. We thought if we want to like achieve a level of Have enough toolbox to engineer the bacterium. You would take about 10 years. So we look at the east Luckily east has been a major workforce in synthetic biology for decades. So there are a lot of things you can do with east So to start with you just mix the two microbes in the magical ratio So they can co-exist and after Three to five days you can have this kind of like pretty thick material. This is a four-day culture You can just like pull it up from the air liquid interface and then you have yeast cells embedded in it So the first thing we were wondering like if we can actually make this like a catalytic material So we can have the east which is commonly used to produce a lot of different enzymes So we use an enzyme that can convert and yellow subject into a red product And we fuse this enzyme like anchor it onto the cell those Magics and then we found like this material when it's wet They can convert the chemical into the red product Even when they are dried out they can still do this because you don't really need the cells to be alive once the enzymes are secreted So there's a user use scenario where you can kill the cell and still make a functional material So you can actually pretty much do like all the enzymes you can think of and Functionalities onto the cell those metrics. So in this case you can actually produce enzymes that can do blue pigments Or like basically this is to show we can actually degrade Contaminants and other hazardous chemicals in the environment Then we came into an issue because I don't know if you guys have seen kombucha culture But like there's a sediment at the bottom. So basically the east they are very heavy and dense They tend to sink so we thought like This is not really ideal because we want the computer to be in the material So then we started to play with the density of the growth medium So we kind of like increase the density and try to push the east up to the pellicle So on the left you can see before the engineering of the solution You have all the east like loosely attached to the surface, but on the right you can have like the entire East colony embedded in the cell those metrics So this is why it looks like on the surface. You have a lot of east cells in there So once you bring the cell closer to the material you can do more things for example in this case We secrete enzymes that can break down different positions along the cell those fibers So you can actually tune the mechanical property of that material So this is before producing the enzyme. This is after so you can see this just become very loose And you can see all the cells still get trapped in the metrics by using different enzymes you can have pellicles like this material with different stiffness and These are just to show you can do different characterization to see there is a difference and One funny thing about this we try to make it stronger, but this is naturally super strong So the only demonstration is to try to make it weaker and we try to convince people sometimes It's better to make it weaker. You can still make like different functional materials out of it And of course we want to do sensing and in this case We just use the pre-existing sensors that east have so in this case they can sense and the environmental hormone estrogen and Turn on the expression of green fluorescent protein and what's interesting about this is like they are functional when they are Alive and wet you can actually store this up to four months The east cell are still alive in the metric. You just have to reactivate it in the growth medium And also you can swap out the output from the GFP, which is not very useful Into some enzymes that can actually do by remediation So they can sense contaminants they can remove the contaminant and Then the final demonstration we thought you'll be really cool If we can actually do like optogenetics that is used lie as an input and use the bacteria I'll use the east sorry to produce an output. So we engineer a Optical circuit so they can actually sense blue light and then produce an enzyme that produce bioluminescence So this is a mandatory school logo photo, which is very common outside media lab So you can see by using different engineering like we have different east strings We can have different resolutions and We can tune the resolution by control the growth rate of the east or like on the right You can let it grow for a longer time. You have a better resolution So those are the things we have done. So what we are thinking is like this is a 2d material kind of thing What we want is volume. We want a lot of volume. So we turn to YouTube for inspirations This is a small-scale one. I believe a lot of people seem like they can actually do this in a much larger scale So some of them in these YouTube videos, they actually use east as the catalyst So there's an enzyme called catalyst in east that can convert peroxide into oxygen and it's a miracle in nature This is like the best like most efficient enzyme you can use So in this video, they use like a chemical as a catalyst But if you use east you can kind of have the same effect So we were thinking this is what we've been trying to do right now It's like if you can actually start with very little volume of liquid and then you can like just add Peroxide and you can have about a hundred times increasing volume and we are also Like doing darker evolution. So what we think would be really useful is now you can have a living material That's actually you can do evolution on the material properties So for example, like here you have the density of the cell you can make it magnetic. You can make it more adhesive and And this is a another demonstration like they can actually Take up the metal ions. So if you engineer metal binding protein into the east It's basically like a plug-and-play system because there are just so many things you can do with the lab strength of east So you see this environmental asian image the black dots meaning like they've taken a metal ions and And also you can produce a lot of different kind of antimicrobial Microbials to kill pathogens Because we know like bacteria solos is actually like one of the most popular won't dressing materials So if you can actually incorporate active ingredients into it, that would be pretty cool Besides killing microbes what we are trying to do now is like they can actually provide a lot of growth factors to direct differentiation of stem cells already like immune cells What would be really cool to me like we seem to like a problem before is about like e-sales being really dense This would not be the problem in the space So if we can actually provide them like a new grab a low gravity environment They can form like a solid phase very homogeneous distribution kind of like livi material so East has been used for devices for point of care like point of detection because they can actually provide a lot of Medical relevant molecules that human use so we're thinking like maybe this is an opportunity We should really look into that and With that I would like to thank a lot of people. I work together in this work specifically people at Imperial and also Brandon here and The George Sun at the Belcher lab Thank you