Forget Growing Weed—Make Yeast Spit Out CBD and THC Instead.

WE AS A species would be miserable without yeast. Baker's yeast has given us leavened bread for thousands of years. And I don’t even want to begin to imagine a world without beer and wine, which rely on yeast to convert sugar into alcohol.

Now researchers have turned to yeast to do something more improbable: manufacturing the cannabis compounds CBD and THC. By loading brewer’s yeast with genes from the cannabis plant, they’ve turned the miracle microbes into cannabinoid factories. It’s a clever scheme in a larger movement to methodically pick apart and recreate marijuana’s many compounds, to better understand the plant’s true potential.

The process goes like this. Two different yeasts produce either THC or CBD, depending on what kind of enzyme they carry. Importantly, both carry the cannabis genes that produce CBGA. “CBGA is this kind of central cannabinoid that's the mother of all the other cannabinoids,” says UC Berkeley chemical engineer Jay Keasling, coauthor on a new paper in Nature detailing the technique.

To make THC, that yeast produces CBGA, which then turns into THCA thanks to the yeast's particular enzyme. For the CBD yeast, its own particular enzyme turns the CBGA mother cannabinoid into CBDA. (Alphabet soup, I know, but stick with me.) Now you've got THCA and CBDA, which turn into THC and CBD with the application of heat.

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