How to Make Better Biofuels? Convince Yeast It’s Not Starving
by Adam Hadhazy (Princeton University) Yeast already helps make bread and beer and cranks out the biofuel ethanol, but scientists believe it can be used to create an even more efficient fuel called isobutanol. Normally, yeast only creates a tiny amount of isobutanol. Now researchers at Princeton University have discovered a genetic switch that significantly ramps up production.
The findings, published Nov. 13 in the journal Cell Systems, showed that the researchers were able to increase isobutanol production by roughly five times over that of standard yeast strains by making the yeast much more tolerant to isobutanol’s toxic effects. Isobutanol has about a 25% greater energy density than ethanol and is much better suited for use in vehicles than current ethanol-based fuels. Biofuels can be a renewable and environmentally friendly alternative to petroleum-based fuels.
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In their new study, Princeton researchers have identified a gene involved in the starvation response by yeast to isobutanol. Deleting this gene turned out to profoundly enhance yeast’s tolerance to the chemical. Freed of thinking it’s missing meals when it’s not, the yeast reallocated its resources into staving off toxic effects from higher-than-usual isobutanol concentrations.
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Overall, the genetically engineered yeast cells produced five times as much isobutanol as normal yeast — a promising step forward in developing renewable biofuels as part of the multi-prong strategy in mitigating the impacts of climate change.
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Isobutanol has attracted great interest in the biofuel community because it has a higher energy density, lower hygroscopicity (ability to absorb water), and lower volatility than ethanol. Most importantly, as a fuel, it is much more compatible with existing storage and transport infrastructures than ethanol, as well as with conventional gasoline car engines, so it is possible to make fuel blends with higher content of isobutanol to replace more gasoline. As a bonus, the colorless, flammable liquid can also be upgraded into jet fuel for aviation, a relatively small but potent contributor to global emissions. READ MORE
Critical Roles of the Pentose Phosphate Pathway and GLN3 in Isobutanol-Specific Tolerance in Yeast (Cell Systems)