Team genetically engineers yeast to produce opioids

For thousands of years, people have used yeast to ferment wine, brew beer and leaven bread. Now researchers at Stanford have genetically engineered yeast to make painkilling medicines, a breakthrough that heralds a faster and potentially less expensive way to produce many different types of plant-based medicines.

Writing today in Science, the Stanford engineers describe how they reprogrammed the genetic machinery of baker's yeast so that these fast-growing cells could convert sugar into hydrocodone in just three to five days.

Hydrocodone and its chemical relatives such as morphine and oxycodone are opioids, members of a family of painkilling drugs sourced from the opium poppy. It can take more than a year to produce a batch of medicine, starting from the farms in Australia, Europe and elsewhere that are licensed to grow opium poppies. Plant material must then be harvested, processed and shipped to pharmaceutical factories in the United States, where the active drug molecules are extracted and refined into medicines.

"When we started work a decade ago, many experts thought it would be impossible to engineer yeast to replace the entire farm-to-factory process," said senior author Christina Smolke, an associate professor of bioengineering at Stanford.

Now, though the output is small - it would take 4,400 gallons of bioengineered yeast to produce a single dose of pain relief - the experiment proves that bioengineered yeast can make complex plant-based medicines. "This is only the beginning," Smolke said.