The Digest’s Top 10 Innovations, 3.28.18 release

#1 Faster, higher density yeast for C5 sugars resulting from new understanding of metabolic design

In Massachusetts, researchers at Tufts University have created a genetically modified yeast that can more efficiently consume a novel nutrient, xylose, enabling the yeast to grow faster and to higher cell densities, according to a study published in Nature Communications.

The researchers took a set of regulatory genes, called a GAL regulon, that normally processes galactose – a favorite on the yeast menu of nutrients – and replaced some of the genes with those that become activated by, and direct the breakdown of, xylose. All other genes in the GAL regulon were unchanged. In doing so, they preserved a more natural interaction between the genes that govern feeding and those that govern survival. The new synthetic regulon, dubbed XYL, enabled the yeast cells to grow more rapidly and to higher cell densities.

“Instead of building a metabolic framework from the ground up, we can reverse engineer existing regulons to enable an organism to thrive on a novel nutrient,” said Nikhil U. Nair, Ph.D., assistant professor of chemical and biological engineering at Tufts and corresponding author of the study. The breakthrough may have immediate potential, for example, in cellulosic ethanol processes, where industry is moving towards C5 sugars such as xylose as an alternative to grain-based glucose.