Home' Trinidad and Tobago Guardian : September 21st 2015 Contents A28
body & soul
Guardian www.guardian.co.tt Monday, September 21, 2015
In August, researchers announced they had genet-
ically engineered yeast to produce the powerful
painkiller hydrocodone. Now comes the perhaps
inevitable sequel: Scientists have created yeasts that
can make important constituents of marijuana, includ-
ing the main psychoactive compound, tetrahydro-
cannabinol, or THC.
Synthetic versions of THC are available in pill form
under brand names like Marinol and Cesamet; they
are generally used to treat nausea, vomiting and loss
of appetite caused by HIV infection or cancer
chemotherapy. Genetically modified yeast could make
THC in a cheaper and more streamlined way than tra-
ditional chemical synthesis.
Using yeast could also shed light on the clinical use-
fulness of cannabis-derived compounds. Marijuana is
increasingly embraced as medicine, yet there is limited
evidence that it is effective against many of the con-
ditions for which it is prescribed. Researchers hoping
to separate fact from wishful thinking will need much
better access to marijuana s unique constituents. Mod-
ified yeast may provide them.
"This is something that could literally change the
lives of millions of people," said Kevin Chen, the chief
executive of Hyasynth Bio, a company working to create
yeasts that produce THC and cannabidiol, another
marijuana compound of medicinal interest.
In a paper published this month in the journal
Biotechnology Letters, biochemists at the Technical
University of Dortmund in Germany reported that they
had engineered a strain of yeast that produces THC.
They also have unpublished data to show they succeeded
in creating a yeast strain that can make cannabidiol.
Both yeasts rely on so-called precursor molecules
---not simple sugars, which would be ideal---and can
produce only small amounts of THC and cannabidiol.
But Oliver Kayser, a biochemist at the university, hopes
that he can eventually engineer the yeast to replicate
the full THC-production pathway and has teamed with
THC Pharm of Frankfurt to try to scale the processes
for industrial production.
European regulators, he said, are eager for a way to
create a steady supply of THC and other cannabinoids
without actually cultivating marijuana. "They are in
fear that these plants will be grown and will support
some illegal farming," Dr Kayser said.
The idea is not new. Efforts to get yeast to synthesise
THC date back at least eight years, when Japanese sci-
entists published a study detailing how they inserted
a gene into Pichia pastoris that coaxed it to secrete an
enzyme necessary to produce THC.
But the researchers did not know all of the enzymes
used by the marijuana plant to make THC. Over the
last decade, with the help of cheaper and faster DNA
analysis tools, they have found the key genes.
Dr Jonathan Page, an adjunct professor at the Uni-
versity of British Columbia who helped in these sequenc-
ing efforts, set up a company called Anandia Laboratories
in part to reproduce substances in cannabis with yeast.
His company and Hyasynth Bio, Chen s firm, await
approval from the Canadian government to engineer
their own THC-producing yeast strains.
Dr Page, who holds patent applications for several
of the genes in the THC synthesis pathway, said he
anticipated receiving the go-ahead from the authorities
this year. Other biotech firms are exploring the idea,
including Amyris, a biotech company in Emeryville,
Calif., that has used yeast to churn out products ranging
from the antimalarial drug artemisinin to a patchouli
But all this new biotechnology faces tough competition
from the cannabis plant itself. Marijuana has been so
carefully bred for so many years that it has become a
remarkably efficient producer of THC. Some strains
contain more than 30 per cent THC content by dry
"Right now, we have a plant that is essentially the
Ferrari of the plant world when it comes to producing
the chemical of interest," Dr Page said. "Cannabis is
hard to beat."
For this reason, he and his company also hope to
use yeast to make chemicals found in trace amounts
in cannabis that have shown early promise as potential
Newly risen from yeast: THC
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medicines. These include cannabidivarin, which has
prevented seizures in preliminary rodent studies, and
tetrahydrocannabivarin, which may be an anti-inflam-
matory, among other uses.
In late June, Dr Nora Volkow, the director of the
National Institute on Drug Abuse, spoke at a hearing
before a Senate caucus about the potential benefits of
cannabidiol, which is being studied for disorders such
as epilepsy. Some scientists believe it is the substance
that should be prioritised for production in yeast. (NYT)
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