First it was poppies and their opioids, now marijuana and THC. I’m excited to see this boon in synthetic biology, as researchers borrow enzymes and pathways from the plant kingdom and transform yeast into microscopic drug factories. Last month, scientists made headlines when they completed the first opioid synthesis in yeast. Now, researchers have published that they have engineered yeast to produce the active ingredient from marijuana, called tetrahydrocannabinol or THC. Together, the two discoveries illustrate both the utility of synthetic biology in the drug market – and the current challenges facing the field.
With numerous states across the country legalizing marijuana, THC is in high demand. Beyond recreational use, people are advocating the drug for a myriad of medicinal properties – from treating glaucoma to controlling epileptic seizures. But most of these studies were small and not well controlled. And even when there is an effect, it is often unclear if the results are due to THC or some other compounds in the marijuana plant.
So scientists have again turned to yeast for a purer and more reliable source of the drug. Yeast also offer additional advantages over their plant counterparts: in theory at least, the drugs should be easier and more cost-effective to produce in fermentation vats with simple sugars for food rather than vast fields that are subject to the whims of Mother Nature.
But it isn’t quite that simple. As with opioid production, THC synthesis is so far not very productive, generating just miniscule amounts of the drugs. And, in the case of THC, yeast need to be fed a chemical precursor to produce the drug rather than using simple sugars. Of course, there are also debates about the safety of drug production in such an easy-to-use organism – might it some day be possible to homebrew THC beer?
To be honest, I don’t think so. Scientists are very cautious about inserting safeguards (like chemical dependencies) into yeast strains to ensure that drug production occurs only in proper lab settings. But beyond that, I am confident that researchers will be able to overcome the current challenges facing synthetic biology – like low yields and the need for precursor chemicals. I’m excited to see what comes next!