For now, sulfites are able to kill the yeast that might spoil this wine.

Wine sometimes tastes a bit funky because it was contaminated during fermentation with a yeast called Brettanomyces bruxellensis. This yeast can give wine a variety of interesting flavors like “…horse sweat, Band Aids, barnyard, and burnt plastic…”

Winemakers usually keep this from happening by killing off the yeast with those dreaded sulfites. But for awhile now, people in the know have been worrying about the emergence of a sulfite-resistant form of this yeast. And this is a well-founded fear.

Yeast, like bacteria, are fast growing microorganisms with lots of variation in their DNA. If you hit a population like this with something that kills them (like sulfites for B. bruxellensis or antibiotics for bacteria), some small percentage are probably going to be resistant. These resistant strains can then grow and replace the sensitive ones. The end result is sulfite-resistant yeast ruining our wines.

To try to head off this problem, a group of scientists in Australia has figured out this yeast’s DNA. The hope is that scientists will be able to use this data to determine how B. bruxellensis might evolve into a more resistant form.

Note that despite much trumpeting online, they haven’t really solved any problems with this knowledge yet. They have merely created the tool that might let them solve a potential future problem. And given how cheap and easy DNA sequencing is these days, it isn’t necessarily even an impressive feat of technological prowess.

Still, it may one day prove useful in allowing winemakers to more quickly defeat a sulfite-resistant strain. Which can only be a good thing for wine making.

I don’t want to end this before saying a nice word or two about B. bruxellensis. This yeast can spoil wines but it isn’t all bad.

For example, it gives Belgian beers their special taste. And some winemakers actively seek it to give their wine a bit of a “brett” taste.

Still, a sulfite-resistant form would definitely be a bad thing for most winemakers. So scientists should definitely stay vigilant and be ready to come up with quick solutions using this new tool (and whatever other ones they can find) when sulfite-resistant B. bruxellensis begin to appear.

We Don’t Want the Funk (in our Wine) 13 January,2012Dr. Barry Starr


Dr. Barry Starr

Dr. Barry Starr (@geneticsboy) is a Geneticist-in-Residence at The Tech Museum of Innovation in San Jose, CA and runs their Stanford at The Tech program. The program is part of an ongoing collaboration between the Stanford Department of Genetics and The Tech Museum of Innovation. Together these two partners created the Genetics: Technology with a Twist exhibition.

You can also see additional posts by Barry at KQED Science, and read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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