Yeast Engineered to Produce Cannabinoids

September 25, 2015 | Sarah Tse

A marijuana plant cultivated under a grow light.
Photo credit: devjeff/

Medical marijuana researchers say goodbye to grow lights and greenhouses, having genetically modified a strain of yeast to produce Tetrahydrocannabinol (THC) in test tubes.

With the recent changes in perception towards marijuana use among both the medical community and the public, it should come as no surprise that scientists have now engineered a strain of yeast that can produce the psychoactive component called tetrahydrocannabinol, or THC.

SEE ALSO: Researchers find cannabis compound helps heal broken bones

Stoners everywhere are probably rejoicing and fantasizing about a new world of edibles, where yeast gives bread a dose of THC in the rising process, and maybe even drinkables in the form of THC-infused beer and wine. But prepare for a buzzkill — the researchers from the Technical University of Dortmund in Germany intend the breakthrough to be gateway to new research on the drug’s medical utility.

THC is used to treat nausea, vomiting, and loss of appetite from HIV infection and chemotherapy, but there’s still a lot of red-tape wrapped around the issue, even in states and countries where marijuana is legalized. Marijuana also comes with a multitude of other chemicals whose effects have yet to be fully researched and tested. Prescribing marijuana in its natural form is like “throwing 400 tablets in a cocktail and saying, ‘take this,’” said Yasmin Hurd, a professor at Icahn School of Medicine at Mount Sinai, to Tech Insider. Some companies synthesize THC in pill form, but the production process is laborious and costly.

If the production of THC and other cannabinoids can be regulated in a laboratory setting, researchers won’t have to deal with the restrictions and stigma associated with growing Cannabis plants. With increased access to these compounds, they’ll be free to expand their studies on a variety of cannabinoids and pinpoint their effects on certain diseases. Likewise, those seeking to use medical compounds from marijuana will have an easier time obtaining the drugs in many European countries where marijuana farming is illegal, reports The New York Times.

But first, researchers have to refine the biological logistics and figure out how to make the yeast produce additional cannabinoids. The yeast have been upgraded with genes isolated from the marijuana plant that encode enzymes involved in THC production, but the yeast are still only equipped with the machinery to complete the last few steps of the process. If they can manage to teach the yeast how to make THC out of plain old sugar, similar to how yeast ferment sugar into alcohol, it will become much easier to scale up the process.

The researchers have also had some success with engineering the molecular production pathways for cannabidiol, another marijuana compound of interest to the medical community. In fact, some doctors believe cannabidiol should be prioritized for synthesis by yeast because it has shown some promise for treating epilepsy. Cannabis plants produce it in much smaller quantities, so it’s even harder for researchers to get their hands on it. Other auspicious cannabinoids include cannabidivarin, which could prevent seizures, and tetrahydrocannabidivarin, which may have anti-inflammatory properties.

But there’s a long road ahead, full of DNA analyses, tricky genetic engineering, and smoothing out biological logistics — not to mention future legal and regulatory hurdles. Producing the compounds in industrial amounts will pose the real challenge, according to Kevin Chen, CEO of Hyasynth Bio, who hopes to start selling these yeast-produced cannabinoids. “Large scale stuff is really at the bleeding edge of science with this field,” he told Motherboard.

Once scientists have trained the yeast to supply commercially-scaled quantities of cannabinoids, they can more efficiently test the drug’s action in the body. These modified yeast may transform the field of medical marijuana, but if you’re still dreaming of THC-infused beer, don’t hold your breath.

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