Nature reports on another genetic revolution that’s, um, brewing in Belgium, where DNA researchers are tweaking yeast to make better beer:
Kevin Verstrepen’s lab meetings can be pretty boozy affairs. Twice a week, several members of his group at Belgium’s University of Leuven and the Flanders Institute for Biotechnology gather around a table loaded with black, tulip-shaped beer glasses, together with spit buckets and crackers.
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He wants to build the perfect yeast. His lab is deploying what it is learning about the chemical and genetic basis of beer flavour to breed yeast strains that generate unique flavours and other qualities coveted by brewers and drinkers.
The beer geeks in his lab straddle the worlds of curiosity-driven science and industrial brewing. They study evolution, biochemistry, and even neuroscience through yeast. But they also have contracts with beer makers worldwide, from multinational conglomerates to small trend-setting craft breweries. In an upcoming Cell paper, the lab will report the genomes of some 150 yeast strains used to make beer, sake and other fermented products, a project done in collaboration with a leading supplier of yeast to brewers and a synthetic-biology firm.
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Verstrepen argues that many brewers are still stuck in the nineteenth century when it comes to the yeast they use. “Brewers, especially traditional brewers, are often not using the optimal yeast.” Most use just one strain — isolated from their brewery or borrowed from another decades ago — in all their beers.
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The balance in the freezers is made up by the lab’s creations — completely new strains that have unique combinations of traits. The team makes them by mating different strains and then screening the offspring for the aromas they produce and, more recently, for genes that underlie these traits. This latter approach, known as genetic-marker-assisted breeding, is common in agriculture, and Verstrepen thinks that it will transform brewing.
A Canadian brewery commissioned one of these custom strains when it wanted a full-flavoured Belgian ‘tripel’ that has less alcohol than is typical for the style. Another brewery has asked for yeast that makes chocolatey aromas, a request that has stumped the lab so far.
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Verstrepen’s archive makes the lab a one-stop shop for brewers looking for unique flavours. For example, when Bouckaert wanted “funky” aromas, such as the smell of barnyards or horse blankets, but without the usual accompanying fruity notes, he tried four of the lab’s strains that showed some promise. None was going to work for a New Belgium beer — at least not yet. “Kevin’s research is a little bit out there and on the edges of brewer’s applications,” Bouckaert says. “But that doesn’t mean it will not translate to something that could be huge in the future.”
Natural variation in brewer’s yeast offers much leeway to dial up and down flavours and other traits, but the approach can only go so far, Verstrepen says. Genetic-modification tools could improve on that. “With breeding we can increase flavour 10-fold, with genetic modification we can increase it 100-fold or 1,000-fold, and we’ve done this,” Verstrepen says. “The beers you make are more like banana milkshakes. Is this something we really want to do?” Brewers are excited about the work, but the stigma that surrounds genetically modified (GM) foods means that the lab always uses more conventional techniques such as breeding and directed evolution to make strains destined for industry.