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.


When microbiology is a data problem: Putting science together to make better pictures of yeast

Short: A Portuguese-based group is suggesting that winemakers could have more useful information about choosing a yeast strain if scientists did a better job of putting together data from different kinds of experiments.


Scientific research generates a lot of different shapes and sizes of data. How does anyone make it work together?

Contemporary scientific research has a lot of big challenges, but here are three: funding, replicability, and integration. Funding is a great big gory topic for another day.

Replicability has seen a lot of attention in recent science news: scientists across disciplines have been reporting difficulty duplicating their colleagues’ results when they try to repeat the same experiments. This is worrisome. (Most) science is supposed to be about making observations about the world that remain the same independent of who is making the observations. Two careful people should be able to do the same experiment in two different places and obtain the same results. Well-trained scientists, however, are finding themselves unable to replicate the results described in scientific papers, and the community isn’t sure what to do about it.

Integration – how to fit together large amounts of lots of different kinds of data – looks like a separate kind of problem. Scientists (microbiologists, biochemists, systems biologists, geneticists, physicists…) study a thing – yeast, say – in many, many different ways. They generate data in many different shapes and sizes, using all manner of different kinds of instruments to make numbers that don’t just tidily line up with each other. But, at least in theory, all of those data are about the same thing – the same yeast – and so finding ways to integrate data from different kinds of experiments should massively improve our understanding of how yeast works as a whole.

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An unfortunate opportunity for misdirection, or, lack of evidence to support a biodynamic tasting calendar

A group of New Zealand sensory scientists have just published an article entitled “Expectation or sensorial reality? An empirical investigation of the biodynamic calendar for wine drinkers” with the open-access journal PLoS One. Without any offense whatsoever to the researchers, this is a bad paper, not because of how the research has been done, but because of how easily it’s likely to be misunderstood.

The study’s question was whether tasting wine on a fruit versus a root day, as determined by a biodynamic tasting calendar, affects how the wine tastes. The study’s method was to have 19* wine experts tasteT the same 12 New Zealand pinot noirs on a root day and again on a fruit day (or a fruit day and again on a root day; half of the tasters followed each order), scoring each wine (a few times over, for statistical consistency) as “low” to “intense” on each of twenty factors like “sweetness,” “tannins,” “expressiveness,” and “overall structure.”

The study’s conclusion was that the difference between fruit and root days made no difference to how tasters perceived pinot noirs in any way. That’s unsurprising for two reasons – that the idea of a biodynamic tasting calendar is hogwash, and that biodynamics is a spiritual system that can’t for the most part be relevantly tested by reductionist scientific means – but that’s not my main point.

My main point is that this paper is far too likely to be taken as empirical evidence that biodynamics is a load of nonsense, even though that’s not what the paper says. The paper says that perceptions of what’s in a bottle don’t systematically change between days categorized in a particular way by a calendar devised by Maria and Matthias Thun in 2010. Information about how they devised this calendar is difficult to find online, though I admittedly didn’t try very hard.

The question doesn’t address a core principle or practice of biodynamic agriculture. All the same, it’s far too likely to be inappropriately co-opted to support the “biodynamics doesn’t work when put to the empirical scientific test” argument even though the paper doesn’t support that argument. This danger of inadvertent misapprehension (or deliberate misapplication) is worse because of the relatively few peer-reviewed scientific papers published about biodynamics, which means that this one will get a relatively larger share of attention now and in future reviews than it would otherwise. Moreover, PLoS One is a generalist journal, and so this paper will be read by a lot of people who don’t know enough about biodynamics or wine to clearly distinguish biodynamic-guided tasting from biodynamic agriculture. That’s unfortunate. 

About those two reasons why this article’s findings are unsurprising. The first is that the idea that wine tastes different depending on astral movements just doesn’t cohere with, and indeed is contradicted by, enough other forms of knowledge to give it any credence. Bottled wine changes over time – call it “alive, “if you’d like – but over months and years, not days. And even without attacking biodynamics as a knowledge system, we have a lot of reasons to believe that astral movements don’t affect day-to-day life on earth.**

The second is that biodynamics is a “spiritual” system, which is to say that its efficacy is at least in some ways tied up with belief and personal development. Biodynamics treats the farm as a coherent ecosystem or “single, self-sustaining unit,” of which the farmer is a part. By that biodynamic logic, it makes sense that the caring, positive, trusting farmer is part of the efficacy of biodynamics on a farm, and that removing that person – or, indeed, isolating any one element in the biodynamic system away from the rest for the purposes of a controlled scientific trial – will disrupt the system.

All of that applies to biodynamic agricultural practices which, as I’ve said elsewhere, I think make a good deal of sense for the same reasons that following strange diets often benefits the dieter: in paying caring, positive attention to what you’re doing, you’ll probably do it better. Call it the placebo effect, though thinking about the farm as an ecosystem affected by everything you put into it and a living thing deserving of care is more than just the power of positive thinking; that’s good environmental stewardship. I can’t say the same about the biodynamic tasting calendar.

Of course, the placebo effect usually isn’t a bad thing, either. If opening your favorite bottles on fruit days helps you enjoy your wine more, who am I to say that you shouldn’t enjoy your wine? Just don’t use this new research as a reason why you (or, heaven forbid, someone else) shouldn’t enjoy a biodynamic one.


*Which makes you wonder what was wrong with the twentieth person’s data, or whether someone came down with a cold or had to go home to clean up an overflowing toilet.

**Beyond things like the psychological and sociological influence of full versus new moons, for example, which is a different matter and an important point, given how human psychological influences can ramify.