30 August 2013

New yeast strains efficiently turn bio-waste into bio-fuel

Belgian researchers develop GM yeast to increase fermentation efficiency

Researchers from KU Leuven and VIB have developed new yeast strains capable of converting waste into bio-fuel with unprecedented efficiency. The yeast strains could have real environmental and economic benefits, particularly as the burgeoning industry of second-generation biofuels continues to grow.

Lead researcher Johan Thevelein (KU Leuven/VIB): “These new yeast strains come at an opportune moment. The entire industry is approaching economic viability. We are working hard to further improve our yeast strains to increase their already impressive fermentation efficiency. We hope to further strengthen our leadership position in this growing industrial sector.”

Yeasts are used in the production of bio-ethanol from waste streams. Until recently, producing bio-ethanol in this way remained difficult. No single strain of yeast was capable of converting all sugars in the biomass into ethanol. Pentose sugars – basic carbohydrates with five carbon atoms – proved particularly problematic. In recent years, genetically modified yeast strains able to ferment pentose sugars have been developed, but these lab strains were not suitable for industrial fermentation processes.

Mekonnen Demeke (KU Leuven/VIB) and Johan Thevelein have now cleared this obstacle by changing the DNA of industrial strains of yeast used for bio-ethanol production in such a way that they are able to ferment pentose sugars. At the same time, these strains were made even more robust. The researchers’ new yeast strains also efficiently and quickly ferment various types of biomass into bio-ethanol in real conditions, outside of the lab. This new strain has attracted the interest of the industry because the efficiency with which these yeast strains make bio-ethanol from waste is unprecedented.

The production of bio-ethanol from waste streams, post-harvest waste (e.g., straw, wheat bran, empty corn husks or corn stalks) and wood (waste) is generally considered to be one of the most sustainable and climate-friendly technologies for producing fuels for the transport sector (road and air traffic). In 2011, only 4% of transportation-related energy inputs were renewable, with bio-diesel being the predominant source (86%), followed by bio-ethanol (12%) and green electricity (2%). By 2020, that ratio is expected to rise to 10%.

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The study “Combining inhibitor tolerance and D-xylose fermentation in industrial Saccharomyces cerevisiaefor efficient lignocellulose-based bioethanol production” by Mekonnen M Demeke, Françoise Dumortier, Yingying Li, Tom Broeckx, María R Foulquié-Moreno and Johan M Thevelein was published in the journal Biotechnology for Biofuels.

Source: KU Leuven, press release, 2013-08-30.


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