Yeast, that magical microorganism that provideth bread and beer, can now make narcotics, too. In a much-anticipated update, a team of scientists from Stanford University has engineered a strain of common brewer’s yeast to turn simple sugars into opioid drugs.

Last year, bioengineer Christina Smolke announced that her lab had coaxed yeast into producing precursors to thebaine, an opioid molecule that can be converted into morphine, oxycodone, and heroin. Now, by hacking 23 genes from plants, bacteria and even rats into yeast, Smolke’s lab has worked out how to make microbes manufacture thebaine outright, in addition to the painkiller hydrocodone. It’s “the most complicated chemical synthesis every engineered in yeast,” Smolke told the New York Times.

It’s also one of the most controversial. Yeast has proven itself time and again a valuable asset to the biotech industry, because it’ll happily take up new genes and spit out useful products. We’ve turned yeast cells into factories for all sorts of valuable chemicals, from antibiotics to cosmetic ingredients.

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Yeast growing happily in a petri dish. Image via Stephanie Galanie

But some experts feel morphine and heroine-producing yeast crosses a line. In May, MIT’s Kenneth Oye and colleagues published a commentary in Nature stating that drug regulatory agencies are woefully underprepared to control an emerging biotech science that could benefit illegal drug manufacturers.

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Smolke believes these concerns are overblown. Her new yeast strain, described Thursday in Science, would need to be 100,000 times as efficient to match the drug yields of opium poppies. Put another way, it would take 4,400 gallons of yeast to produce the amount of hydrocodone in a single Vicodin tablet. At the moment, Smolke tells the Times, anyone looking to make illegal opioids “could buy poppy seeds from the grocery store and get higher concentrations.”

And while some critics, noting that Smolke’s lab used brewer’s yeast, claim that we’ll “one day be able to home brew heroin like beer,” Smolke maintains that the process is quite a bit more delicate, and requires sophisticated laboratory equipment. To prove it, her team actually tried growing their hacked yeast under typical home-brew conditions—and lo, no opioids.

Home-brew heroin rings aside, microbial narcotics factories could, in the future, allow us to manufacture legitimate drugs on the cheap. And that could benefit millions who suffer from chronic pain.

[Science; h/t New York Times]


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