UC Berkeley researchers engineer yeast to produce chemicals found in cannabis

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A UC Berkeley research team published a study Wednesday introducing yeast engineered to produce key cannabinoids — the main chemical components in the cannabis plant — from the sugar galactose.

The research team out of the Keasling Lab, led by campus professor and senior faculty scientist at Lawrence Berkeley National Laboratory Jay Keasling, successfully synthesized both naturally occurring cannabinoids such as tetrahydrocannabinol and cannabinoid analogues. Since the study produced a diverse array of cannabinoids, many of which are only found in small quantities in the plant, the study allows these chemicals to be studied more easily and potentially be applied to new medicinal ends.

“My personal interest is to provide the research community the access to a wide range of molecules with different structures, from which there might be discoveries of new drug(s),” said Xiaozhou (David) Luo, a campus postdoctoral student studying in the Keasling Lab and co-author of the study, in an email.

The process of cannabinoid synthesis in this study involved inserting genes in yeast which encoded the enzymes to produce the cannabinoids. The technique yields cannabinoids from galactose, a simple sugar, which is a more cost-effective method than extracting the cannabinoids from the cannabis plant. Keasling compared this technique to “brewing beer,” except the molecules of interest are cannabinoids rather than ethanol.  

Luo said in an email the difficulties the research team faced included figuring out a way to introduce more than 10 genes from different cannabis species into the yeast and “make them all work as we thought,” as well as to produce cannabinoid analogues.

In addition, some of the “unnatural cannabinoids could be excellent therapies,” according to Luo in an email. Keasling said in an email that another benefit is its lower production cost, as chemical synthesis of cannabinoids can cost around $40,000 to $70,000 per kilogram, while using microbes will be able to produce the chemicals for less than $400 per kilogram.

Another potential benefit is reducing the environmental damages of mass cannabis production, according to Keasling. Growing cannabis in fields is known to produce wastewater and pollute the environment through pesticide and fertilizer runoff.

“With production by yeast, the waste will be less and can be easily handled in (wastewater) treatment systems,” Keasling said in an email.  

Now that researchers have constructed a pathway for producing these chemicals, the in-lab technique proposes a variety of new applications. Since certain cannabinoids are only found in “minute quantities” in the plant itself, the yeast method allows scientists to spotlight these rarer substances, Luo said in an email.

According to Robert Payne, an employee at Hi-Fidelity — a marijuana dispensary on Telegraph Avenue —  the cannabis industry could be impacted by widespread microbial production of cannabinoids.  

“(This new technique) may have huge benefits, but why mess up a good thing?” Payne said.

Contact Sasha Langholz at [email protected] and follow her on Twitter at @LangholzSasha‏.