The oldest tool in biotechnology just got a major promotion, from beer brewer and bread maker to the creator of drugs and artificial life.
For the first time, scientists were able to paste an entire set of genetic codes into yeast in just one step. Using the same techniques, scientists could transform the microbes into living factories, which produce expensive chemicals in an earth-friendly manner.
Yeast are remarkably good at stitching long segments of foreign DNA together, and then reading them. But those stringy molecules must be prepared and inserted correctly. Scientists at the University of Illinois pioneered an extremely-efficient way to slip new genetic material into yeast, reported in the journal Nucleic Acids Research.
"Assembling genes into a biochemical pathway using a DNA assembler is similar to building a toy train," said chemical engineer Huimin Zhao, who led the research. "Each cart is an equivalent of a gene, which is connected to each other in an ordered manner at the same time."
Zhao and his team at the University of Illinois simultaneously inserted eight genes into yeast cells, coaxing them to produce zeaxanthin, a food dye that occurs naturally in saffron and paprika. With a bit more work, his team could harness the single-celled organisms to produce expensive antibiotics.
Other researchers have inserted genes into yeast to make drugs, but the previous method using circular DNA molecules called plasmids wasn't very efficient. Scientists could only insert a few genes at a time, and only around 20 percent of the yeast responded successfully to the plasmids.
The new technique employs straight DNA strands with special segments at the ends that match up with part of the yeast genome, helping it integrate into the yeast genome. The result is a 70 percent success rate.
The same tricks could come in handy for researchers who want to create artificial life. In that case, the yeast would be used to stitch the man-made fragments of a genome together. That's important because even the best synthesizers can't make DNA that is long enough to contain the entire recipe for an organism.
"The method needs some optimization to make it work more efficiently and assemble very large recombinant DNA molecules such as a bacterial genome," says Zhao.
Image: Yeast are used to produce nutrient-rich products like Vegemite, one of the finest foods on Earth. Credit: erictitcombe / flickr