Talking Biotech 374
Bioengineering Yeast for Better Beer
Dr. Charles Denby- Berkeley Yeast
Dr. Kevin Folta- Podcast Host
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Kevin Folta: [00:00:00] Hi everybody, and welcome to this Week's Talking Biotech podcast by Colabora. Now, 20 years ago, I moved to Gainesville, Florida, and the beer scene here was a disaster. I came from Madison, Wisconsin, and you had all these great micro breweries and you could even buy a picture of Capital beer and drink it behind the student union out on Lake Mendota and watch a band or whatever.

I mean, it was a fantastic place to spend some time on my scientific career. When I came to Gainesville it, it was like being in shock because you'd go out to dinner and you'd say, what beer do you have? They'd say, oh, we got everything. We got Bud Light, Miller Light, Coors Light. Miller, Coors, Budweiser, and if you're fancy, we got Budweiser, Amber Bach, or Michelob, Amber Bach

So pretty thin. Choices. And so that was, you know, kind of a bummer. You know, when you came from a great beer town and then you go to one [00:01:00] that has none. It's a real shock. So the problem was, is that everything that was here lacked all the interesting flavors that were in modern micro brew beer, craft beer, whatever you call it.

eventually we caught up and the number of different breweries here. That opened a lot of really nice stuff. And then bringing in product from beyond , so it's not uncommon to go anyplace and be able to get a significant variety of different flavors in aromas. And as a scientist who has an interest in flavors in aromas, this is really a big deal for me because I can pick out different notes that correspond with different.

Trees that we've studied in fruits and vegetables and things like that. So it's really cool to understand this harmonization between the basic ingredients that go into the fermentor along with the yeast, and then that fermentation process run by the yeast converts sugars to alcohol and carbon dioxide.

But it's [00:02:00] not just doing that. Yeast, it's a bustling hub of metabolism. There's diverse suite of all these different enzymes acting on a complexity of substrates, sometimes creating chemistries that flirt with the drinker sense. So it's, it's all the things that ize that, that go up behind the nose that give you all the different flavors and aromas and brewers have known this for a long time, and yeast genetics has been at the core of brewing in.

but what if biotech approaches could be part of genetic improvement in providing a faster way to essentially breed yeast to be better, give new instructions in an effort to produce like novel flavors and aromas to improve fermentation parameters or maybe remove off flavors that are not necessarily a good thing in a mug of.

Well, that's exactly what Berkeley yeast is doing. So today's [00:03:00] guest is Dr. Charles dbe. He's the CEO and co-founder of Berkeley Yeast. So welcome to the podcast, Dr. Dbe. 

Charles Denby: Thanks so much for having me. 

Kevin Folta: So I'd like to start out with a statement of the problem and last I checked. That beer isn't broken. So what is this drive in the brewing industry for novel flavors and aromas and beer, or are there other traits that are important to the fermentation process that you can adjust with the yeast?

Charles Denby: Yeah. All right. So you're, you're really diving right into it. I love it. So yeah, what we're doing at, at Berkeley yeast is using bioengineering to create flavors that don't ordinarily come from yeast. And of course you're absolutely right. Beer is 100% not broken. But what it is is it's, it's absolutely been an evolution over time, right?

If you look at the history of beer You know, I like, I like to I like to look all the way back, back [00:04:00] to like the beginning of human civilization and, and beer really was one of the original bio technologies. And, and, and may have even been the linchpin of human civilization, right? People were started, you know, switching from.

Hunter gatherer to farming cereal crops like barley, and found that if you ferment it well, it's a lot more stable and it's a lot more sterile than if you just put grains in a silo. Right. So looking all the way back to 10,000 years ago, beer was very different from what it is today, and that's also true even if you look back.

50 years. You look at the, you look at the composition of beers that are on the shelf today versus then, or even 10 years ago. It's been, it's, it's, it's been a continuous evolution. So I think th there's always been a spirit of. Innovation and refinement in the beer industry. And I think the thing that's really exciting about what we're building at Berkeley yeast where we're, you know, again, bioengineering, yeast to create [00:05:00] flavors that are desirable in finished beer is that it enables you to create.

Stuff that just otherwise would be, that just otherwise wouldn't exist. Right. So like, let me start with a a, a basic example. Let's say you're a brewer and you want to create a beer that tastes, that has more pineapple flavor to it, right? And some beers already have pineapple flavor to it, and you might think of a couple different ways that you can generate that flavor.

One is you could add pineapple juice, right? But, or extract or whatever. But I can tell you that experiment won't go very well because the pineapple, the. Because of some of the nuances of the brewing process, you're not gonna be able to retain those pineapple flavor compounds through the, the, the brewing process.

Or another thing that's been really popular as of late is finding particular hop cultivars or hop preparations that give rise to some of those pineapple flavors. And that's [00:06:00] really interesting and that's been a really neat source of flavor variation in the beer industry over the last couple of decades.

But I can tell you that if you add a hop cold, that maybe it has pineapple character, it's probably gonna turn out different. Every different preparation of hops that you use, like one year it might taste a lot like pineapple and maybe like some other flavors. And then the next year, maybe it'll only taste a little like P pineapple and more like.

Other flavors, right? So the ability to use bioengineering to create yeast that make that flavor and only that flavor is really powerful and it creates a really neat tool for the brewer to innovate more in this space. 

Kevin Folta: Yeah, and you touched on something that's really important that sometimes people don't think about implant biology is that when you talk about the pineapple or the the hops, is that the flavors and aromas of that particular crop are going to be dictated by so many factors.

How much fertilizer, how [00:07:00] much water was it sunny days before they harvested it? So there's so many environmental variables that cause. Compounds of interest to fluctuate. And so by being able to engineer the yeast to create it from some sort of common substrate gives you as the brewer, more control of the stability and predictability of the outcome.

Is that 

Charles Denby: right? Oh man. Yeah. You are just totally nailing it. And so they're all sorts of interesting. Benefits that arise from getting the yeast to make the flavor as opposed to getting it from a specialty crop. Right. So you just nailed it with consistency. Right. And, and, and. If you're asking a yeast to make it inside of a precisely controlled fermentor, it's basically like a bioreactor for the, for the, for the you know, for the for like you, you can control the, the pH, you can control the.

Temperature you can control. You know, the, the starting sugar constitutes you can control all of these things and you can dial all of [00:08:00] these things so you can make a perfectly consistent product from it. But then there are other interesting dynamics here too. Like, let's say you're a brewer and you make a recipe that you absolutely love.

It turns out to have this like, Again, pineapple aroma to it that you just love and you're, and then you're thinking, okay, well and maybe you, maybe even you win a gold medal with it and, and it's generally loved, you know, beloved by your customers. So then you say, okay, well I got something that the world wants.

Maybe next year I'll make 10,000 barrels of it. Or, or, A hundred thousand barrel of it. Well, not so fast, like where did you get that specialty crop and can you get 10 or a hundred x more of that specialty crop for next year? That's gonna be really hard. And oftentimes in order to get, let's say you're doing it through a fruit, you might have to go talk to a farmer or, or a hop cultivar, for example.

You might have to go talk to a farmer and say, Can you plant 10 or a hundred times more of this crop? [00:09:00] And, and they might say to you, okay, sure, but like, you're gonna have to commit to buying all of it over the next five to 10 years. Right? So it just makes the process of sourcing ingredients much less dynamic if you have to rely on these long agricultural cycles.

Whereas if you're getting it from the yeast, not. and you ensure the consistency. You can make sure that you can scale your products up and down, you know pretty much instantaneously. . 

Kevin Folta: Oh, very good. And, and so let, let's talk a little bit about flavors in aromas. So we talked about pineapple, for instance.

And when we think about pineapple as somebody who works with flavors in aromas myself, like we work on the genetics of flavor in aroma, and there are certain compounds that when you put them together, so these are volatile compounds that when you. Put this stuff in your mouth. The warmth of your mouth blows this stuff up behind your nose, you have al faction that puts together a picture in your brain of what this compound or what this food is, what are its [00:10:00] chemical constituents.

And so when we're talking about something like pineapple, there's a whole bunch of other, well, a whole bunch of different compounds that are responsible for pineapple. That come together as kind of an orchestra that give you, that, give your brain that picture of pineapple. So is really that what the yeast is emulating, that you have yeast that can produce these compounds that are mimics of naturally occurring compounds that give the brain the picture of fruit without the fruit actually being.

Charles Denby: That is exactly right. Yeah. And, and so you're, you're absolutely right. The primary determinant of pineapple flavor we found in our hands to be an Esther called Ethyl eight. It's actually, but you're absolutely right. It is. An orchestra and you know, the, the sort of the neurons that are firing is like, you know playing a note, like having, having that orchestra play, play a different note.

I couldn't, I love that analogy. And so yes, the yeast is [00:11:00] creating those, that same note, like that same composition of flavor compounds and it's hitting your neurons the exact same. Cutting into a freshly grown or like a freshly cut pineapple would, would, would stimulate those same neurons.

Kevin Folta: Yeah. This is really cool stuff. So are there yeast that just naturally do this? They just, by virtue of the enzymes they produce, produce that ethyl x anate or well, I guess we'll talk about the bioengineering later, but are there naturally occurring yeast that create these compounds? Because people selected them, because they liked that.

Charles Denby: Yes, that is really a really in insightful comment. Absolutely. The sort of domestication of yeast has selected for yeast that produce really desirable flavors, but that can only take you so far in comparison to what is possible using bioengineering. Like, let me to, to, to use this example of ex of, of Ethel [00:12:00] hex oh eight or hec.

The enzyme, so you're right that there are enzymes in yeast that are capable of creating that compound. The thing that's interesting though is that if you're just using sort of the, the general tools of. A sort of domestication, which is more or less allowing for random mutations to occur in the genome of these brewing yeast strains, and then selecting the one that you like the most.

There's only so, so far you're going to be able to get with that, and it's going to take. You know, decades and decades, if not centuries, to select a flavor profile that you really, really love. Okay. And so what we're able to do with bioengineering, which I think is, I, I can get further into this but what I think is really interesting is we're able to insert enzyme genes that code for enzymes into the genome of, of any yeast.

such that they will specifically produce that [00:13:00] alh and not some of the other compounds that might happen when you're just randomly mutagen the yeast during a domestication process. So it's, it's, it's extremely precise and also allows you to dial in the exact level of that compound that you want pretty quickly, right?

So if you want, if you say, oh, I really like this yeast strain, it has this pineapple note. Well, do you want to toggle it up a little bit? Maybe you want five times more. Maybe you want to toggle it down. You, maybe you only want 50% of it. Well, the, the tools that you have using bioengineering allow you to do that pretty.

Kevin Folta: That's really cool. But you, you talked about yeast domestication. How different are the yeast that are used in brewing or in wine making than the ones that occur naturally? Just like the ones that are sitting on the grapes out in the vineyard or the ones that are on the barley. What, what is the, how much is domestication played a role in modern brewing?

Charles Denby: Yeah. It has played an [00:14:00] immense role in modern brewing yeast. Like if you were to go out into, and there's some, by the way for, for, for, for, for folks that are enthusiastic about reading the primary literature about this kind of stuff. There's some very cool papers which you know, I can, I can point you guys towards, but like in particular there's a, a lab in there's a lab run by a guy named Kevin Verin.

Who published a recently published a cell paper about you know, they did genome sequencing across, you know, a thousand different yeast strains and, and, and many, many, the, the large majority of which are used in various fermentation processes. And there's also other papers that, that look across thousands of different chino yeast genomes as well, like but what some of the really interesting findings there is that yet the differences between brewing yeas.

and their ancestor, their ancestor being, you know, a yeast strain. If you were to go out into some primordial, you know, forest out that has never been touched by [00:15:00] humanity, like, and you found the yeast strains that are present there they are extraordinarily different from what you see in a modern brewery.

And like, just to give you a se, like a, probably the clearest example of this is, Brewing yeast are really good at consuming the sugars, the fermentable sugars in barley, like glucose malto especially, and Malto Trio is another one of the fermentable sugars. But if you were to go take that ancestral yeast strain from which it, it arose, it wouldn't be able to.

It wouldn't be able to consume that moose. And, and, and that has been an evolution over time. And you, you can actually see these large genetic rearrangements in the genome of brewing yeast that are unique from either the ancestor and also unique from some of these other strains, like these wine strengths.

And wouldn't you the brewers yeast are really good at fermenting maltose cause that's a rich sugar source in, in barley. And then [00:16:00] wine yeast are much better at fermenting fructose, and they're also very good at fermenting glucose, right? But fructose is unique to you know wine fermentation com compared with brewing, right?

So the most obvious place you'll see it is in their sugar com consumption capacities. But there are other more subtle ways that you see very major differe. One other really interesting, kind of noteworthy is that why yeast have two copies of their genome, right? They're called deployed similar to humans, right?

We have two copies of our genomes, whereas a common industrial brewing yeast is, is, is, is typically. , highly polyp ployed. Oftentimes there are four copies of their genome, and oftentimes there, there are large, you know, sort of chunks of their genome that are either missing in one or two or three copies, and sometimes they're amplified and present in many more copies.

So, ton of genetic variation between these yeast strands and, and they've been massively impacted by by, you know, the inner, but by, by, you know, human use and, and informative beverages and, and [00:17:00] beyond. 

Kevin Folta: Yeah, so there, so I didn't know that about the ploy differences. That's really cool. So, so basically when you take yeast and you domesticate it for either say bread, wine, or beer, you're basically taking the wolf of the microbial sacra sei world and domesticating it in the dachshunds and, and and pit bulls.

Right? 

Charles Denby: Exactly. You're, you're, It's crazy, but, and, and the interesting thing is that, that in the yeast world, it wasn't really appreci. Right. You can, it's, it's pretty easy to appreciate in the, in, in the world of wolves and dogs because you can see them and you can see how differently they behave. But in the yeast world it, this picture only got clearer when we have these wide sort of sampling of different genomes for different industrial yeast that are servicing different industrial purposes.

So the last 10 years has been a real, like, especially since kind of the advent of. Large genome sequencing efforts. It's [00:18:00] been really interesting to see just how domesticated these different yeast strains have become. 

Kevin Folta: So the yeast is the machine. Can you tell me more about the brewing process in general and, and where it starts and where it ends?

Charles Denby: The brewing process is really pretty simple from a conceptual standpoint, right? You start, it's just four ingredients and water bar. Yeast and hops, and you start like, you know, barley growing in a field. You harvest the barley, you, you kill it, which is basically you, you're drying it out. And then at the brewery, you're adding that kiln barley to water warm water, hot hot water, and that's called mashing.

But what it really is, is it's basically like for, for the chemist, it's basically like doing a water extract. Right. You're, you're allowing all of the fermentable sugars to come out of the barley into the water and all the amino acids and all the other things that [00:19:00] are, that are Necessary for a healthy fermentation or coming out of the barley.

Then you cool down that liquid and then you add yeast to that liquid. And like I said, it's rich with fermentable sugar. So the yeast convert those sugars into ethanol and a whole host of other compounds, and that process usually takes about mm, four to seven days. And finally, during different parts of this process, you might add, hop.

At different time points, right? So if you add hops during the. The mash or that sort of water extraction step then you'll get a lot, you'll extract a lot of the sort of bitter compounds that give rise to the bitter flavor. You're most associated with these really hoppy IPAs, for example. And then if you ad hops later, like after most of the sugars have been fermented, for example, then you get much more.

The flavor compounds extracted from those hops, right? So the upshot is that when you think [00:20:00] about where, where all these chemicals that like, okay, so beer is this massively. Like has a massively complex chemical composition. And when you think about where all of these different chemicals are coming from many of them are, are starting with, coming from the barley and then they're being transformed by the yeast.

Like for example, the fermentable sugars are being transformed in ethanol and all the whole suite of different flavor compounds and then different chemical compounds are being extracted from the. As well. And so that's what gives rise to this, you know, super complex finished beverage that, that, that you and I enjoy.

Kevin Folta: That's good. So what, what are some of the most important secondary metabolites, like some of the compounds that really give beard distinction? . 

Charles Denby: Oh man. I love that question. So I think we already mentioned this class of compounds called Esthers, and just to kind of give you a sense for how Esthers can drive different flavors.[00:21:00] 

Let's say I put a course and a Budweiser in front of you on a table, maybe the average drinker would say, you know what? I think these tastes pretty darn similar, but what you would notice is that. The Coors beer has more of like a pear or a fresh cut apple flavor in aroma, whereas the Budweiser is gonna have more of that banana flavor in aroma and those compounds come from different Esther.

And so Esthers are massively, and as we got into earlier, a different Esther gives rise to pineapple flavor and yet a different Esther might give rise to more of a 2D fruity flavor. So Esthers do are, have an enormous potential to. Flavor and beer. Other classes of compounds that are really interesting are terpenes, which I know as a, as a, as a, as a, as a plant flavor chemist, you know, all about.

Like for example, Lin Wool and geranium are known to be some of the primary flavor determinants in certain covas of [00:22:00] hops. So terpenes are also really important. And, and, and, and the list goes on, right? There are lactose that drive stone fruit aroma. and there are th compounds that drive sort of tropical fruit aroma just to name a 

few.

Kevin Folta: Yeah, that's really interesting. Lin Lu is the one from fruit Loops cereal. So when people think about fruit Lo, so when you're thinking about this idea of this aroma orchestra, this chemical orchestra that creates aroma, Lin Lule in Fruit Loops, you would never think about being an important con component of beer, but it's just.

That you don't really perceive it in terms of picking it out of the orchestra, but it's there. And if it's missing, you would notice. And it's the same thing with like Basil. A big player is Lin Lu and Eugenol like these other compounds. Lin Luol is a really important one, but you don't think it tastes like fruit loops.

It's just there in this tiny little amount that in conjunction with the rest of the flavors gives your. Kind of an image and and determines [00:23:00] liking and sweetness and all the other interesting things that that go on. When we're tasting things, it's really kind of cool how it works. So how much of this is coming from the grains versus the hops versus the yeast?

Charles Denby: Yeah. Okay. So it, that definitely depends on the style of beer that you're making. There are some I, I, I'll say generally speaking The grains have a pretty major impact and the yeast also has a very major impact. One of the things not to, not to digress too far here, but like, one of the things that I find really interesting just to like, just to kind of gain a quick appreciation.

For this, the process that yeast is doing in terms of changing the molecular composition of its substrate. I like to remember that with bread fermentation. If you have bread fermentation, similar, similar to beer making, is it starts with a cereal. Wheat being a cereal crop, and water, and [00:24:00] then the yeast fer.

and, and more specifically, the, the wheat is processed in flour, right? So you have flour and water. The thing that I find really amazing is that if you have flour and water and you try and. Survive off of it. You, you won't survive for very long, but if you ferment the, the flour and water into bread, now all of a sudden you can survive, you know, practically indefinitely.

And that just goes to show just how complex the set of. Bio transformation events is when you know, when bread is being fermented. And the same is actually true in the beer making process. People don't appreciate this as much in, you know in, in, in, in current times. But like yeast is beer is also like an amazing source of nutrition.

This was way more appreciated like a century ago now. I think the fact that people typically drink beer for a combination of the flavor quality. And kind of euphoric sense that you get from [00:25:00] consuming alcohol. People kind of forget about all the, the, the, the nutritional value associated with. . Okay. But that's all to say barley.

And then the, what yeast is doing to that barley are the biggest drivers. And then what's also interesting is that there are new, especially, well, there are different styles of beer where the flavor and aroma are, are dominated by the flavor of hops. And nowhere is this more clear. Sort of modern IPAs where a lot of hot material is going into them, and the flavors that you get from them are dominated by hops.

And you might, you might be thinking about very sort of vegetable fruity juicy floral, all those flavors in aromas can, can be, can be, can be kept from hops. And then yet still there are styles of. That leverage fruit during, during the process. And, and those, and those flavors are being driven again by that, by that other specialty agricultural product.[00:26:00] 

Kevin Folta: Yeah. And I, I won't mention any name brands, but there's a couple IPAs out there that I really like, or I like IPAs in general, but there's a couple out there that have something in the hops or the ye hops yeast combination or whatever it is, where I get kind of an off flavor, kind of almost like the socks.

You know, compound and, and I'm am curious, you know, and it may just be me, I'm real sense, everybody's different sensor collection and different sensitivity to the different aromatic compounds. So that's why everybody's experience is a little different. But I guess my question is, if you got yeast doing all this work with creating metabolites, how likely is it for them just to make the things you want?

I mean, can you get off flavors and how do you propose to eliminate. 

Charles Denby: Oh yeah. That is such a great can of worms to open. Yes. Enzymes tend to have different levels of specificity, meaning one enzyme may take only one substrate and make only one product. Another [00:27:00] enzyme may take one product, one substrate and turn it into 10 different products.

Right? And so we absolutely see that in practice, like one of our, one of our strains. That produces tropical fruit flavor during the fermentation process, this strain called tropics. We found that when we first put that enzyme into the yeast it produced a really desirable flavor, but also it produced an undesirable off flavor.

So then what we had to do is we had to go back to the drawing board and do some protein engineering to make sure that the product. That it was producing was only the desirable one and it, and very limited amount of the off the undesirable one. So that's just a really micro example of how enzymes can, can be made to be more specific.

But I think the other point that you're making, which is, which is a really important one, is that. When you're when you're getting flavor from a complex [00:28:00] product like, like a hop or a fruit, it has just like, it has dozens if not hundreds of different flavor compounds that are gonna affect the quality of the final product.

And you can't really pick and choose which ones you get. Like maybe you get more of the good ones, but, but some of the off flavors are necessarily gonna be coming along for the ride. And that, I think is what bioengineering of yeast, such a powerful tool in delivering beers that are more enjoyable to beer 

Kevin Folta: drinkers.

Yeah, all this is really fascinating and it really adds to the understanding and appreciation of this special kind of product. So, , we're speaking with Dr. Charles dbe. He's the c e o and co-founder of Berkeley Yeast. This is Collabs talking Biotech podcast, and we'll be back in just a moment. Now we're back on collabs talking Biotech podcast, and we're speaking with Dr.

Charles dbe. He's the c e o and co-founder of Berkeley Yeast and they're [00:29:00] engineers of yeast taking the domestication process. One further and a whole lot faster to produce more flavorful beer. And this is all being done using modern biotechnology. So could you tell me a little bit more about your journey?

I know that you were in academia for many years and now you've been working with Berkeley East. How did you come up with the idea and how do you really start to turn a good idea into a business? 

Charles Denby: I, as you mentioned, I started in academia. I actually moved to Berkeley to get a PhD in yeast genetics and evolution.

When I was doing that, I was really studying very basic biology, asking very fundamental questions about. How the genetics of yeast work. And when I graduated I was really interesting, interested in doing something a bit more applied with my education. And I, I had had a, a front row seat to all of the amazing things that were going on in bioengineering at Berkeley at the [00:30:00] time.

And perhaps the most, or for me, the most interesting work that was being done. Was in modern metabolic engineering, which was really being pioneered by a professor at Berkeley named Jake Ling. So I managed, and a lot of the stuff that I was interested in grad school was sort of was, was. Sort of dovetailed with the kind of research that they were doing in this bioengineering lab.

So I you know, eventually was able to convince Jay to take me into his lab as a postdoc. And there is where I really gained an expertise for how you engineer. Microbes like yeast to create new things or eliminate other things, right? Basically to, to specifically alter the composition of, you know, fermentation.

And I joined Jay's lab thinking that I was going to engineer yeast to make biofuels. And actually I ended up. Working on that quite a bit and published some, some nice papers about it. But while I was doing that, I also got really interested in making beer. You know, I was home brewing [00:31:00] beer in my garage with some of my buddies and like you do when you take up a new hobby, I started reading all about it and, and learning about the biochemistry of, of the beer making process.

One of the things that I thought was really interesting was when I started diving into. Okay. What are the flavor compounds that give rise to the most desirable, hoppy flavors? In my favorite style beer, which was IPAs. Right? And it turned out that the flavors were these terpene compounds that I, I spoke briefly about a second ago, which is like Leno and Geranium.

And it just so happened that this metabolic engineering lab that I was in were world experts at engineering microbes to make various different types of terpenes. Not necessarily for flavors. Like one of the most famous ones was actually an anti-malarial drug that's based on ter and terpenes are a very, very diverse set of chemical compounds.

But the fact that we could engineer yeast, This, you know, complicated terpene [00:32:00] for that, that that's an anti-malarial led me to think, okay, well maybe we can engineer yeast to make some of these terpenes that give beer their hobby flavor. So in my, you know, copious spare time, I ended up building a prototype teamed up on, on, on the effort with one of the graduate students in the lab at that time, who's one of my co-founders, her name is Rachel Lee, and we ended up building a yeast strain based on a brewer's yeast strain that was capable of making some of these flavors that give hops their hoppy flavor.

And this was like a really cool you know, side project that really turned into a main project. And the, the, the sort of commercial implications only kind of gradually occurred to us. At the end of the day, what we were looking at was just saying, okay hops is like a billion dollar industry and most of the hops that are, you know, grown and sold in in, in the hops in the beer industry are for flavor.

And well, we can engineer this yeast to make the flavor, [00:33:00] so maybe we have something. It has some commercial potential and that's really what led us to start the business. And the last thing I'll say about that is In order to kind of launch the business, we applied for one of these small business innovation research grants from the US government.

So the thing that I love to that I love to to appreciate when we think about our journey to kind of get from the ivory tower out into the world and, and bringing these new technologies into the market, is that you. Government grants starting a small business were indispensable for us launching the company.

So one very brave program manager was really, you know, I'm sure all of our colleagues were saying, really, you're gonna give a grant to some folks that are studying how to make better beer. But she she was a visionary. So thanks to to Ruth Schumann for, for seeing the potential value in the technology.

So that's really how we got out of the lab and into more of a business setting. , 

Kevin Folta: S B I R is a great program and, and I review [00:34:00] those all the time and I love the innovations that are out there. So I'm glad you got funded through that. That's really cool. You mentioned this whole idea though about the yeast making the compounds that were usually coming from hops.

Is this like a, a major goal of Berkeley yeast to be able to somehow maybe emulate some of the most critical compounds that are present in a good I p A for. 

Charles Denby: Yeah, it, I mean, it's a really excellent, it, it had been a, a very excellent starting point for our business, right? Because, you know, the hops has been an immense source of innovation in the brewing industry, and that's because.

The composition of flavor compounds that can be generated through hops and, and breeding different varietals and growing them under different conditions. And has, has sort of op, I think opened the eyes to the modern beer drinker about what, what, like, what is possible, like in terms of beer flavor, just from these simple ingredients.[00:35:00] 

And so we use that as inspiration for, okay. What, like what are the flavor compounds that are most desired by the beer drinker? And can we engineer yeast to do it? And if we can it makes it easier for the brewer. It also makes it more sustainable. Right? It makes the, the proximate if like, let's just say that.

I mean, to be clear, I don't think in the next, you know, in, in, in, in, in the near future, we are going to be able to replace the amazing sort of chemical complexity that comes from hops like that. That's always gonna be a source of inspiration. It's always gonna form a backbone of, of, of, of, it's one of the traditional ingredients, right?

It's always gonna form the backbone of beer. But if you can take a beer that's created. Let's say four. And these are arbitrary numbers to, to the average listener. So I apologize. But like if, if you were to take a beer that's made with four pounds of hops for every barrel of beer, and you could use yeast to [00:36:00] create, let's say 75% of that flavor, and then you only have to use one pound of yeast for or one pound of hops for barrel of beer you create, then you can make an enormous impact on the sustainability of.

Beer making process and, and talking about sustainability in two different senses. Like on the one hand hops require, like growing specialty crops, whether it's hops or fruit or whatever, requires a lot of natural resources in terms of water, in terms of nitrogen in terms of energy. And but in the, in the second sense, the reality of the situation is 10 years from now, 20 years from.

There's not gonna be enough water to grow the amount of hops that are currently being grown, right? It's just that water is gonna be needed for, for drinking, for, you know for, for other purposes beyond just irrigating these specialty crops. So I think as we transition to a more sustainable set of ingredients, engineered yeast is gonna be a [00:37:00] really important part of that 

Kevin Folta: solution for.

Well, it's not just the hop flavors. You also have a very strong piece of the portfolio in tropical flavors. And is that because they work well in beer or because they're me not metabolically challenging to engineer in or. You mentioned the pineapple before. I think I said yl acetate, which I think that's the banana one.

Exactly. Not the pineapple one. Yeah. Yeah. So, so what are so people know this because if you have a good hef ays and you get lots of that good banana flavor in there for instance, But are there yeast that are really good at making these different kinds of chemistries? Even the ones like I noticed s guava in there too.

Charles Denby: Yeah. What the reason that we went after those tropical fruit flavors and aromas is because these compounds are highly sought out in beer from various sources, whether it be from, literally from like a guava like a guava puree. Or from a hop cultivar that happens to have a lot of [00:38:00] those flavor compounds that are reminiscent of guava and passion for it.

So we knew that that was a flavor compound that was desired by the beer industry. So and, and that really came from a lot of our of our early sort of market research and to, to kind of rewind back to when we were engineering yeast to make these terpene compounds, those terpene compound. , they drive sort of these floral and citrus flavors and aromas and, you know, we, we, we we, we put those out there and asked and, and, and got feedback from brewers.

And one of the, one of the questions we would ask is like, okay, obviously we asked them how do they like the beer? But then we said, okay, well if you could use the same general idea, the same tool of engineering yeast to make any flavor compound, what would it be? And people said, tr like hundred, you know, we, we did.

With hundreds of brewery interviews, and by far the most common response was tropical fruit flavors. And you know, as a, as a, as a flavor cist yourself, I'm [00:39:00] sure. And, and, and, and again, to go back to that analogy of, of the orchestra, you know, I can't explain why. Humans have evolved to like you know, tropical fruit flavors.

But I just think that there's something about those tropical fruit flavors that strike the neurons in a way that it just is hitting that reward pathway. It, that may be related to the fact that now, now I'm getting real armchair human evolutionary biology with it, but like that may be fa due to the fact that all the way back in the day, All the way back to kind of hunter gatherer times, fruits were like a rich source of sugar, and that was really important for sustaining, you know human biology, right?

This is probably the best place to get the nutrients that you needed to survive. So I suspect that, that the desire for tropical fruit like wired into our, our dna and also like that d and that [00:40:00] presents as being wired into our neurobiology. , 

Kevin Folta: I think you're exactly right. I think it's the sugar was a rare commodity in hunter gathering times.

And so when you found it, you gorged on it and you recognized the aromas and flavors that would travel with it as being desirable. And that's kind of wired in, that's hardwired into us. And also, you know, lots of vitamins, vitamin C, vitamin A, all the good carotinoids, all the other stuff that comes along with the fruit to make it attractive for animals in the process of propagating the.

And, and, you know, spreading the seed, you know, for a given fruit. We are just animals and so if it can attract us and keep us on it longer we could have potentially been seed spreaders, but it was something that benefited us too. So I think you're right on there. That's pretty cool. That's pretty wild.

So what about the changes in genetics? How much of this is really a, as yeast breeding in the traditional sense versus bio. 

Charles Denby: To give an example of, of what goes into [00:41:00] our bioengineering process. So when we're looking to create a new yeast string, let's use the example of the yeast that, that creates little wool.

Well, the first thing that you need to do is you need to find some set of gene that encode the new chemistries required to make that new flavor compound. Okay. So in the case of lineal we know. The terminal. The last step in the biosynthetic pathway is what converts the building block for a terpene into that final terpene compound.

And so the first step that we needed to, to do was to figure out which enzyme we could find out in the natural world that we could put into the yeast, and it would. In the way that we had wanted. And then we also found that there were two other genes in yeast metabolism that could actually drive more of the precursor to lenal towards that enzyme.

Okay. And then the, the thing that So that's really step one. It's just identifying a set of genes that [00:42:00] can do the thing that you want. But then what happens is when you put that set of genes for the very first time into a yeast strain, what happens is, well, first of all , it may, that strain may, it may make exactly the amount of lin oil that you want, but it might make less than you want, or it might make more than you want.

And not only that, but by virtue of putting these new enzymes into the yeast, you can also potentially cause. Sort of collateral damage to the yeasts function, right? So if, so, these are the real things that make engineering a good, robust commercial strains to be a bit of a challenge. So the way that we deal with those challenges is, Usually will, first of all, we have ways to optimize the expression of the genes that we're expressing.

So again, to go back to this example of the, of the final enzyme and, and lenal biosynthesis, one of the things that was really [00:43:00] interesting was when we expressed that first enzyme, it was actually an. That we got from mint, a mint plant. What we found is that it didn't make very much little at all.

And so being in this, you know, world famous metabolic engineering lab, which also had a lot of plant biologists at it we, I, I went and talked to my colleagues and, and trying to figure out, okay, why is it that this isn't, well, it turns out that an interesting aspect of making of, of, of terpene biosynthesis biology is that in those plants like mint.

Terpenes are made in a particular organelle called chloroplast, right? And. The way that that enzyme is trafficked to that organelle, to the chloroplast is it has this little liter sequence. It's about 70 amino acids at the beginning of that enzyme that targets it to the chloroplast and bef. And then once it gets to the chloroplast, it lops off that, that liter peptide.

And then only then [00:44:00] is it a highly functional enzyme. So that was an aha moment for me. I said, oh, Well you know, the yeast doesn't have a chloroplasts, doesn't know what this litter sequence is doing. Maybe I can just express the enzyme without that litter sequence and it'll be much more effective. So, sure enough, that's exactly what we observed.

And, and now our strains were starting to produce Len at the levels that we were, we were wanting. But then we also noticed that different strains would have different abilities to. Sugars, right. So a key point of this research for us, or this r and d effort was to get that yeast to consume sugars the exact same way or to function in the exact same way as the parents trained.

So for that, we basically just took those three genes and hooked them up to different sets of promoters until we were able to create a. That made exactly the amount of little that we wanted, but fermented those sugars and, and, and performed in every other way. Exactly. How the parents trained it. [00:45:00] So that's like kind of the whole the whole tip to tail process of engineering a commercial yeast.

Kevin Folta: Well, and it's kind of cool that you can do this in yeast because a lot of people don't appreciate, you know, yeast. You can do so many of these molecular gymnastics in yeast and have a yeast with different genetics in two days. You know, a, a fermentor full of it rather at least a test tube full of it rather than working with things like, you know, plants or animals.

You know, that yeast is a pretty agile. 

Charles Denby: Yeah, it, and, and the implications for, you know, making making beer that delight consumers is that you can deliver innovation much more quickly, right? You can imagine if you look at the most popular hop cultivar today, It's a, it's a, it's a cultivar called Citra.

And if you look back on how long it took from the first, from first breeding Citra to today, it's like on the order of 30 years, [00:46:00] right? So it took, I don't know, 10, almost 10 years just to create that. That, that cultivar probably took another 10 years of growing it at small scale, maybe scaling it up a bit, getting it into the hands of various different brewers that took another 10 years, and then to actually scale it up to like what it is today, yet another 10 years.

And that's just part of the fact that plant breeding is really difficult. And also because farming you know, is, is not nearly as dynamic as growing east. Right? So the thing that's cool here is. We can create. dozens and dozens if, or hundreds, thousands of different yeast strings and test all of them.

Figure out which the best one is, and then we can scale that up to whatever volume you want very quickly. Yeah. 

Kevin Folta: And, and the, here's a good description of plant breeding. The one part you left out kind of touched on here at the end is, is that, When in the development of Citra hops, you probably planted five acres with, you know, a [00:47:00] thousand plants per acre.

That 900 and, well, 99.9% of them didn't taste good or were complete garbage or got disease or dyed from drought or whatever, that it was this one plant that they had to grow for years to get it to flower, to where you could begin to use it in evaluation of its utility as. Beer flavor additive. So, I mean, it's a real challenging question.

It really is. I guess the last thing I would ask you about is, you know, how common is genetic engineering or bioengineering in brewing in general? How frequently is this kind of strategy used in beer yeast or wine 

Charles Denby: yeast? . As far as I know the very first brewery to use a bio-engineered yeast strain was Fieldwork Brewing Company back in 2018.

And this was performed with our yeast eventually became super Bloom, which is this prototype that creates some of. Terpenes that give rise to floral and citrus, [00:48:00] hoppy light flavors and aromas. And so we were delighted to find out that as soon as we got our grass certification from the FDA showing that our strain was perfectly safe that that this brewer guy named Alex Tweet at at fieldwork was very happy to take it for a test spin.

And he created a. From that, that was just spectacular. It was, it was, I felt like, at least in my circle, it was the talk of the town for a little while. This idea that you could use, that you could use bioengineering to create more flavorful beers. And since then we've been offering this, this yeast and a number of others to, you know, the craft beer world especially.

And so now we have, you know, hundreds of customers that are using bioengineered yeast from Berkeley yeast. And then we've also worked in the wine industry as well. And so we ha have another, a number of wine customers that's not quite as far along, but, but, but those offerings are, are sort of [00:49:00] on their way to the.

Kevin Folta: So if I'm a brewer and I have interest in a specific type of flavor or maybe a specific note, flavor note that would differentiate my product, is this something that I could come to your company and say, help me with this and let's make a custom yeast that I could use as a proprietary element in my brewing.

Charles Denby: Yes, absolutely. We have brewers, we have winemakers come to us asking for there, there's two general flavors of, of, of customization that we get. One is, Hey you know, I really like your super bloom yeast. But it's really good at making ales and, and I actually really like loggers. So and I have this logger yeast that I've been using.

Since I opened the door as my brewery, and I don't want to totally wrap it, like totally wholesale change what my loggers taste like. So could you take this logger yeast and could you engineer it to make some of those flavors? And the answer to that is, is yes, definitely. And we do that. We've done that for a number of breweries.[00:50:00] 

And then the other question is, okay, I'm really interested in. This particular flavor compound, like, you know, maybe it's pineapple, right? So they would come to us and we would say, yeah, of course we can engineer yeast to make pineapple. And the development process, don't get me wrong, it's not like it happens overnight.

Depending on how far along we're on the research and how challenging of bioengineering problem it is, it might take. A day it might take, it might take a week, it might take a year, it might take two or three years, right? So but, but absolutely customization is, is is certainly something we're willing to do.

And that's, those are oftentimes our favorite projects. 

Kevin Folta: Well, all this is really fascinating. It's a great application of biotechnology and improving something that many of us enjoy. It always is good. And, and the thing I like about this is, this is a great example of how, how. People who are interested in communicating about biotechnology can describe this kind of process because it's exciting and it gives us more diversity and more options, and it's super cool stuff.

So, [00:51:00] Dr. Charles Debe, thank you so much for joining me today. And if people wanted to learn more about your company, where would they look? Online or maybe on social media? 

Charles Denby: Yeah, you can find us@berkeleyeast.com. And there are links there to our Instagram, which we're, we're, we're fairly active on.

But thank you so much for having me. It's been a real pleasure chatting with you today. Yeah, 

Kevin Folta: thank you. And thank you for joining me and keep me posted as we go forward. If I, well, I always say if, when, I mean, when your next exciting product comes out, I would really be happy to talk to you again. So thank you very much for joining me.

Yeah, absolutely. And as always, thank you for listening to another episode of Talking Biotech podcast. Go crack a cold one. Take a big swing and think about the flavors that are there. What are all the notes that make the beer you like, the one you like, and what is it that contributes to it? Is it the yeast, the hops, the barley, the malts, or you know, all the above.

It's a really interesting [00:52:00] example of a conspiracy where multiple genomes come together to create some sort of an output that we all appreciate. So thank you very much for listening. This is a Talking Biotech podcast by Collabora, and we'll talk to you again next week.