Engineered Yeast Could Open up a DIY Painkiller Market

Thanks to a little genetic engineering, microbes could make the painkillers of the future. Researchers from the United States and Canada reported this week in Nature Chemical Biology that they have created a strain of brewer's yeast that will ultimately be able to turn sugar into morphine.

Right now, this strain can only perform the first half of the chemical recipe for morphine. However, researchers found the ingredients for the second half back in April, and yet another study outlines how to link the two halves of the recipe — all in yeast. It won't be long before someone puts two and two together. "We're likely looking at a timeline of a couple of years, not a decade or more, when sugar-fed yeast could reliably produce a controlled substance," John Dueber, a study co-author and UC Berkeley bioengineer, said in a statement. The techniques could pave the way towards cheaper, more effective painkillers — but it could also open the door to homemade opiate concoctions.

Most of the world's supply of morphine and other opiates comes from poppy plants, reports Rachel Ehrenberger for Nature. These producers are picky about their growing conditions and hard to regulate, also serving as a source for illegal heroin trade. Microbes on the other hand are a lot more low-maintenance.

"So bioengineers have looked for enzymes in other plants, and even in humans and insects, that could carry out the desired reactions when inserted into a microbe’s genome," Ehrenberger writes. "But so far, no one has been able to engineer the whole process into a single organism."

Enter yeast. It's easy to manipulate, and scientists know just about everything there is to know about its genome. Yeast is already being used to make malaria drugs, so other pharmaceutical products might not be that much of a stretch.

Researchers were able to pin down a key enzyme in yeast that's integral to the morphine chemical recipe in yeast. Armed with this knowledge, they genetically MacGyver-ed regular, old brewer's yeast (Saccharomyces cerevisiae), so that it had the required chemical machinery to make reticuline, an intermediate compound halfway down the opiate pathway. Once all of the the bits and pieces of the recipe are strung together, brewer's yeast should be able to make opiates pretty efficiently and at a low cost. Reticuline can be used to make thousands of different compounds that go into cancer treatments and antibiotics. These compound pathways could be mixed and tweaked to create new entirely new drugs, as well.

But, such ease raises some serious questions. Namely, how does one regulate a microbe that can make heroin?

Whatever regulators and law enforcement choose to do, they better start thinking about it now. "This is a public health issue, and a big one. It’s safe to assume there would be great demand for this stuff," Kenneth Oye of MIT told Azeen Ghorayshi of BuzzFeed News. (Oye and two colleagues also published an opinion piece on the subject in Nature Chemcial Biology.) With heroin overdoses on the rise in the U.S., homemade concoctions could cause serious abuse problems.

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Helen Thompson writes about science and culture for Smithsonian. She's previously written for NPR, National Geographic News, Nature and others.