Without yeast, we would be miserable as a species. For thousands of years, baker’s yeast has provided us with leavened bread. I can’t even picture a world without beer or wine, which rely on yeast to convert sugar into alcohol.
Now, scientists are using yeast to do something even more unlikely: producing the cannabis chemicals CBD and THC. They’ve converted brewer’s yeast into cannabinoid factories by inserting genes from the cannabis plant into the microorganisms. It’s part of a bigger effort to dissect and reproduce marijuana’s various chemicals in order to better comprehend the plant’s full potential.
This is how the procedure works. Depending on which enzyme they contain, two distinct yeasts create THC or CBD. Both possess the cannabis genes that make CBGA, which is significant. “CBGA is this type of central cannabinoid that’s the mother of all the other cannabinoids,” explains Jay Keasling, a chemical engineer at UC Berkeley and coauthor of a new study outlining the process in Nature.
To manufacture THC, that yeast makes CBGA, which is subsequently converted to THCA by a yeast enzyme. The CBD yeast uses its own enzyme to convert the CBGA mother cannabinoid to CBDA. (I know, it’s alphabet soup, but bear with me.) Now you have THCA and CBDA, which when heated, transform into THC and CBD.
The final section is quite similar to what is going on with the cannabis plant. It’s doubtful that you’d get high if you ate raw cannabis because it’s primarily THCA. The conversion of THCA to THC occurs only when heat is applied. (However, as cannabis flower cures, minor levels of THCA change to THC.) Edibles work because producers utilise a process called decarboxylation to convert THCA to THC.
Working with the original plant is dirty and complex, which is why academics and cannabis corporations are interested in other methods of manufacturing cannabinoids. To begin with, growing the substance requires a significant amount of time, water, and energy (if done indoors). It’s also difficult to extract some cannabinoids from flower. If you’re solely looking for CBD, for example, your extract may be tainted with THC. This is especially important if you want to extract CBD for use as a medicine—been it’s proved to be quite successful in treating epilepsy, for example.
What’s up, Know-It-Alls! If it’s your first time, how much weed should you try?
Having a vat of yeast producing pure, non-psychoactive CBD promises to make production much easier. “Being able to make it without contaminating it with THC is a really valuable thing,” Keasling says. Especially since the FDA may want to speak with you if you mistakenly give a psychoactive chemical to a patient.
It’s also possible that cannabinoid-producing yeast will make it easier to research cannabis in the first place. We’re dealing with a plant that’s incredibly complex, with over 100 distinct cannabinoids identified so far. Some of these substances are more common than others; for example, modern cannabis strains are high in THC, as producers have bred strains to …