What is the terroir of synthetic yeast?

I recently published* an article with the unlikely-sounding title “What is the terroir of synthetic yeast?” The piece is open-access for anyone to read at Environmental Humanities, though it relies on a fair bit of jargon-heavy social science theory. For that reason (and plenty of others), many people might not get past the title. And reading only the title, you might well think that I’m talking about wine made with synthetic yeast and its special bouquet de la laboratoire.

But you cannot buy wine made with synthetic yeast. Much wine is made with commercial wine yeast, genetically improved through careful breeding for desirable traits through what is fundamentally a centuries-old process of controlled mating and selecting progeny with desirable characteristics for further mating. In the United States, Canada, and Moldova, you may also find wine made with one of two genetically modified yeast strains (GM yeasts are illegal for winemaking purposes elsewhere), constructed by molecularly inserting a small number genes into yeast genomes using techniques only a few decades old.

The creature known as synthetic yeast, in contrast, is—or, rather, will be—the result of making comprehensive changes across an entire yeast genome, building whole chromosomes following the plans for that comprehensive redesign (find more detail here). “Synthetic yeast” will be the product of assembling those redesigned chromosomes in a single little yeast body. Six of sixteen chromosomes are complete with the remainder well on their way to completion.

Even then, however, synthetic yeast-fermented wine won’t be hitting the market anytime soon. An in-progress version of synthetic yeast engineered to produce raspberry ketone has been used to make raspberry-scented chardonnay, but that experimental wine can’t legally leave the lab. So what does its terroir have to do with anything?

Terroir, roughly “sense of place,” is about connection. (Terroir is also used as a euphemism for “this is schmancy wine and you should buy it,” and occasionally as a way of politely saying “I think this wine tastes like dirt,” but I’m not interested in those uses here.) Terroir—the perceived ability to taste that a wine is from a particular winemaking locale—is about using the experience of drinking wine as a means of creating connection between you, the drinker, and a place, a tradition, and a sense of unique identity.

Synthetic biology and other genetic biotechnologies applied to making food are, in contrast, about calories and nutrition or about technical improvement (and, at a different level, about making money for biotech companies). Synthetic foods are placeless; they come from noplace** and can, at least in theory, go anyplace. Some future synthetic yeast might make “better” wine, if “better” is defined in terms of technical perfection rather than uniqueness of expression and connection to tradition. Engineered yeast and algae might in some future world possibly deliver complete proteins to hungry people, but might also encourage policy-makers to think of food only in terms of delivering calories and forget or dismiss its many more-than-caloric roles.

What is the terroir of synthetic yeast?” isn’t necessarily a question with an answer. But it is, I hope, a way of enjoining that as we build the future, we build a place in which food is still about building connections, and that we resist employing technologies in ways that estrange us as eating and drinking bodies from the places in which we live.

*Published recently, but written well over a year ago, as academic publishing in the social sciences and humanities often goes. Speed is important in the natural sciences, where multiple groups may be competing for precedence and where researchers tend to work in large groups publishing many papers so that it’s important to have finished results published quickly so that later papers can cite them. In social sciences and especially in humanities, both of those conditions are less likely to be true: researchers are rarely in direct competition (for reasons too complex to detail here) and people tend to work individually and to gestate new ideas at a slower pace. I originally wrote and presented this paper at the 2016 Symposium for Australian Gastronomy, a beautiful and enthusiastic gathering of researchers, producers, and splendid Australian comestibles.

**Of course, they have to come from somewhere, even if that somewhere is carefully de-emphasized. Terroir, as I mention in the article, is also a reminder that peculiar local conditions of production matter to the products of science and technology, too, not just for artisan agriculture.

GMO yeast in wine and how to find them

The vast majority of wine does not involve genetically modified organisms (GMOs). Let me repeat, the vast majority of wine does not involve GMOs. On to the rest of the story:

Whether wine contains genetically modified organisms (GMOs) is a question I’m asked often. In general, the answer is no. Genetically modified grapevines aren’t being used for commercial winemaking (though not for want of trying). Two genetically modified wine yeasts have crossed the commercial production threshold, but not worldwide. One, the un-charismatically named ECMo01, available only in the United States and Canada, has been engineered to produce an enzyme that degrades urea. That’s a useful property because urea in wine can become ethyl carbamate, which the World Health Organization thinks is probably carcinogenic enough to be worried about it.

The other, ML01 (which rolls off the tongue much more easily), is legal in the US and Canada as well as Moldova, and seems to have won more traction (though not, I dare say, because it’s available in Moldova). ML01 includes genes for two non-Saccharomyces cerevisiae proteins: a malate permease from fellow yeast Schizosaccharomyces pombe, and a malolactic gene from the lactic acid bacteria Oenococcus oeni. Together, those molecules allow ML01 to import malic acid into the cell and convert it into lactic acid, granting ML01 the rather magical ability to perform both alcoholic fermentation and malolactic fermentation simultaneously, all by itself. In addition to speed and convenience, this one-stop fermentation is advertised as a route to fewer wine headaches. Lactic acid bacteria can produce biogenic amines, which can produce headaches and other unpleasantries in sensitive people (I’m one of them); eliminating the need for those bacteria should eliminate the biogenic amines and those symptoms.

For reasons which are probably obvious, North American wineries using these GM yeasts don’t exactly go shouting that news from the rooftops, fewer headaches or not.

What if you wanted to identify whether or not any given wine was made with a genetically modified yeast? You’d go looking for the modified gene, right? This isn’t as simple as it sounds, and not just because genes are very small. The genes that distinguish ML01 and ECMo01 are also found in other common wine microorganisms; detecting ML01, for example, means ensuring that you’re not just detecting the presence of perfectly normal malolactic bacteria.

The authors of a recent paper in the International Journal of Food Microbiology handled these problems with a conceptually simple solution to identify ML01 in mixed microbial company. They used PCR – the polymerase chain reaction, or the standard means of “looking” for genes that constitutes the bread and butter of virtually every molecular biology lab these days. PCR amplifies a very specific DNA sequence, determined by “primers” that line up with the genetic sequence you’re looking for, so that even a tiny amount of that genetic sequence in a sample can be detected. By choosing those primers to line up with the joints at either end of the signature ML01 genes – the scars left over from its engineering procedure, essentially – they could target the engineered yeast to the exclusion of both O. oeni and unmodified S. cerevisiae. By using quantitative PCR, which adds some fancy fluorescent chemistry to the basic PCR process to provide a rough idea of how much of that specific genetic sequence is in a sample, they could distinguish between large quantities of ML01 indicating that it was used for primary fermentation versus small quantities suggesting accidental contamination

The goal, in this paper, was to offer a means of establishing whether GM yeasts are being used illicitly in countries where they’re illegal as well as a test against ML01 contamination in factories where it might be produced near non-GM strains.

That’s how to find GM yeast in wine if you’re a biologist. If you’re not, you’re left with less precise methods. One: exclude wine from outside North America and Moldova. Two: exclude organic wine and wine from companies which expressly declare themselves non-GM-users. Three: recognize that the general ethos of a winery probably gives you a good idea of how likely they are – or aren’t – likely to use ECMo01 or ML01. Four: invest in a PCR machine.

*See, for example, this Australian report from 2003, or this Cornell proposal from 1996, along with numerous research projects investigating the concept.

 

“Fit-for-purpose” yeast from the AWRI

The Australian Wine Research Institute (AWRI) has created a quick-read summary page on their ongoing project to develop “fit-for-purpose” yeast: yeast strains designed to facilitate specific flavor profiles for specific applications. They’ve already developed and released (through AB Mauri and Anchor) several strains including two interspecies hybrids — Saccharomyces cerevisiae crossed with S. kudriavzevii or S. cariocanus — and low H2S-producing strains. More are being tested in Shiraz and are likely to emerge over the next 3-5 years. The AWRI is making a point that this research is Aussie-focused — their argument is that similar work being done elsewhere is creating yeasts not necessarily suitable for Australian wine styles — but no doubt their results will end up helping non Australian-industry levy payers, too. It’s worth noting that their development strategies rely on good old traditional genetics strategies and not genetic engineering. They’re not inserting genes from other species into yeast; they’re breeding different yeasts together, encouraging yeast to mutate (that is, spawning lots of random changes in their DNA with chemicals and stress) and looking for useful mutations, and using contemporary genetics to understand which genes do what. For a quick explanation of why I’m glad that they’re sticking with traditional genetics strategies instead of creating GMO yeast, check here.

Whether you’re excited about the prospect of using tailor-made yeast to target particular flavors or whether you’re in the don’t-inoculate-my-wine camp and hold that fermenting with yeast from the environment is the only or best way to terroir-full wines, it’s hard to argue that knowing more about yeast is a bad thing. Developing new commercial products may be an increasingly major research driver as scientists need to look for support from private sources. Furthermore, ending up with a new product you can hand to someone is a tangible way of saying, “Here, look; our research really is applicable and relevant to real-life winemaking!” Regardless, projects like these continue to provide an umbrella for basic research on yeast genetics and wine flavor development. And maybe not tomorrow, and maybe not next year, but in the long run, that’s something that ends up helping everyone.