Percival hopes that the work Lallemand has done in America will start conversations across the Atlantic and that, when it chooses to launch the product there, the systems and processes will have opened up. Hackbarth agrees that this is only the start of the conversation around genetically modified consumables, and that beer is the perfect medium for it.

“We need to start the discussions around the ethical use of gene editing, and a great place to start is in beer,” he says. “It is a low-risk segment of popular culture available to all classes and cultures. The potential opportunity for innovation through gene editing is too great for our industry to pass by.”

Whether the argument for genetic modification has been won or not, the researchers are pressing ahead. Both Lallemand and Berkeley see no limits as to what is possible. Giving yeast the ability to produce terpenes and lactic acid count among the simplest modifications, and there is a lot more research to come. Exactly what those innovations might be are still tightly under wraps, but both Rice and Denby floated the removal of the gene that produces diacetyl to reduce lagering times, the ability to ramp up or slow down ester production, and the possibility of speeding up alcohol production using the genes found in fast-fermenting Norwegian kveik yeast.

“There are the laws of thermodynamics—you can’t add yeast to a beer and it ferment in five seconds—but within that there is immense potential,” says Denby. “We spoke about hop replacement and that was our thing when we were scientists coming out of the lab, but having talked to hundreds of brewers the message is how can we brew better beer, how can we create value in different ways.”

As if genetic modification weren’t controversial enough, one of the ways in which the Berkeley lab hopes to create value is through engineering yeasts that produce cannabinoids. As cannabis slowly becomes legal at a state level throughout the U.S., Keasling is looking at how to capitalize on its production. He has already engineered a yeast that can convert simple sugar into the high-inducing THC and non-psychoactive CBD in a fraction of the time, emissions, and cost. That could have major implications for the pharmaceutical industry, where THC is used to reduce nausea after chemotherapy and CBD is used to treat seizures in children. But it might have its uses in brewing too, as breweries start to infuse their products with CBD and take advantage of the alleged relaxation benefits and hangover relief.

“I think it’s going to be really interesting to see where this space goes,” says Keasling. “We had someone in from a brewing company who licensed the strain, and we talked to them about how they see it going in the future, and it can go one of two ways: either they use the yeast to produce pure cannabinoids and add it to the drink, or to brew and produce the amount of cannabinoid you want in a single vessel.”

Keasling says they are still doing tests on how alcohol and THC would behave and interact when produced at the same time, but is excited by the prospect. As head of the lab where both the hop compound yeast and his own cannabinoid yeast were produced, he knows the opportunities for modified brewing yeast better than anyone, and is certain it will become the norm in the industry.

“To be frank, when we started this work I just considered it academic,” Keasling says. “I assumed no one would be interested in GMO yeasts, so I’ve been pleasantly surprised. We’ll be able to add pretty much any flavor you want, if we can’t do it already. I don’t see any limits—it’s more what will people accept and what people want.”