These ‘cannayeasts’ should make it possible to turn sugar into pure forms of many different cannabinoids, and to do so more cheaply than farming.

Jay Keasling at the University of California, Berkeley, who led the team behind the work, said: “It gives us access to all these rare cannabinoids that might even be better therapeutics. “

Our bodies produce cannabinoids to help regulate everything from memory to appetite. Marijuana plants make more than 100 chemicals that can also bind to the cannabinoid receptors in our nervous system. Extracting the cannabinoids such as CBD or THC from plants, or making it from scratch, is difficult and expensive and Mr Keasling says the genetically modified yeasts will produce pure cannabinoids more cheaply.

“We can beat the economics of growing it on farms,” he says. “In part, it’s because there is a lot of manual labour in clipping the buds and all the things you have to do to grow cannabis.”

He and his team discovered by accident that they can produce previously unknown cannabinoids by changing what the yeasts are fed. So by making it possible to produce and study rare and formerly unknown cannabinoids, the cannayeasts might lead to new treatments for a range of disorders.

Keasling and his team have formed a company called Demetrix to commercialise the cannayeasts. A growing range of food ingredients such as vanilla and saffron can also be brewed in this way. And Keasling’s team is best known for creating a yeast that produces the antimalarial drug artemisinin.