"For the consumer, the benefits are high-quality, low-priced CBD and THC: you get exactly what you want from yeast", Jay Keasling, a professor of bioengineering at UC Berkeley, said in a news release.
The report made no note of California's many cultivators who emphasize regenerative farming and use permaculture systems on their outdoor cannabis grows. Using yeast could massively reduce marijuana's impact on the environment. It is being investigated as a therapy for numerous conditions, including anxiety, Parkinson's disease and chronic pain.
Researchers looked in marijuana for other cannabinoid-producing enzymes and found prenyl transferase. "Inexpensive, purer sources - like yeast - could make such studies easier".
Thanks to this new yeast, Keasling noted, there is "the possibility of new therapies based on novel cannabinoids: the rare ones that are almost impossible to get from the plant, or the unnatural ones, which are impossible to get from the plant".
But the product contained more THC than the label suggested, leading to the positive test.
Marijuana farms are increasing in size and scope, and in California, commercial marijuana cultivation operations have been blamed for polluting local waterways with pesticides and fertilizer runoff. One study estimated that California's cannabis industry accounted for 3 percent of the state's electricity usage. In the past exploring the medical use of marijuana has been challenging due the high expense of extracting the cannabinoids from the plants. From that, a long list of cannabinoids can be produced, including THC and CBD, the latter of which you can now find touted as a cure-all at your local gas station. They readily convert to CBG, THC and CBD when exposed to light and heat.
The boffins used a process that stuffs different genes into the yeast to co-opt its metabolism so that instead of turning sugar into alcohol, it converts it into other chemicals.
To produce cannabinoids in yeast, Berkeley synthetic biologists first engineered yeast's native mevalonate pathway to provide a high flux of geranyl pyrophosphate (GPP) and introduced a hexanoyl-CoA biosynthetic pathway combining genes from five different bacteria. Heating the microbes switched the cannabinoids into their active forms. "That's the beauty of the process", said Keasling.
Although some of the steps in this cannabinoid factory line have been reported before, this work is the first time it's been done in one go, in one cell.
Kesling's team was also able to engineer the yeast in such a way that it will transform various fatty acids into cannabinoids not seen in nature.
Keasling founded a company called Demtrix in 2015, and it licensed the technology to use yeast fermentation to produce cannabinoids.
"But when you read about cases of patients who have seizures and are helped by CBD, especially children, you realize there is some value in these molecules, and that producing cannabinoids in yeast could really be great", he said.