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Home-Brew: Scientists Tweak Yeast to Grow Morphine

Image: Yeast

Yeast cells producing the yellow beet pigment betaxanthin, which UC Berkeley researchers used to quickly identify key enzymes in the production of benzylisoquinoline alkaloids (BIAs), the metabolites in the poppy plant that could lead to morphine, antibiotics and other pharmaceutical agents. William DeLoache / William DeLoache at UC Berkeley

Researchers have figured out how to get yeast to produce morphine, codeine and other similar drugs and have immediately urged regulators to control these drug-brewing yeasts before people start trying to make them at home.

They genetically engineered simple brewer's yeast, Saccharomyces cerevisiae, and came up with a strain that can make very complicated plant compounds that include opioid drugs such as morphine, as well as some antibiotics and muscle relaxants.

It's an important technical step, because now these drugs have to be synthesized directly from plants—an inefficient process. The yeast process isn't that efficient yet, either, but once it's perfected and scaled up, it will lead to easy and cheap ways to make the drugs in large quantities.

"Because of the potential for illicit use of these products, including morphine and its derivatives, it is critical that appropriate policies for controlling such strains be established so that we can garner the considerable benefits while minimizing the potential for abuse," John Dueber and colleagues at the University of California Berkeley write in their report, published in the journal Nature Chemical Biology.

Specifically, what they did was to synthesize reticuline, one of the compounds found in poppies, using an amino acid found in sugar called tyrosine.

It's caught the attention of experts already.

"Many pharmaceuticals are already made by yeasts and bacteria at high yield commercially," said Dr. George Church, an expert in genetics at Harvard Medical School and the Massachusetts Institute of Technology.

Fears rise over synthetic drugs crisis 2:17

"This sort of metabolic engineering optimization is fairly straightforward. Once the recipe is published it becomes very easy to reproduce it -- something that any DIYBIO user could do." DIYBIO stands for Do-It-Yourself biology, and it's a name given to a group of amateur synthetic biologists.

Christopher Voigt of the biological engineering department at MIT points out that the method isn't very efficient just yet, and won't appeal to do-it-yourself drug manufacturers.

"Considering a dose of morphine is 30 mg, this means that 300 liters of yeast would have to be grown for one dose," he said.

But, Voigt predicted, it will happen.

"As the commentary suggests, it is going to be possible to 'home-brew' opiates in the near future. Yeast can be consumed, of course, so there would no need to separate the product. Imagine if the pathway were improved so that a glass of yeast culture grown with sugar on a windowsill provided the 30 mg dosage needed."

But there's promise for better drugs down the road, also.

"Such processes would also lead to the possibility of further development of more effective painkillers," said Paul Freemont, an expert in synthetic biology at Imperial College London.

"Although this study and others represent an important landmark in achieving this, it throws open the whole debate on how such biomanufacturing processes can be safely regulated."