Trillium FiberFuels is developing a xylose utilization technology that utilizes an enzymatic pathway as opposed to the more typical genetic engineering approach.

One of the key challenges to commercializing cellulosic ethanol is the utilization of pentose sugars, especially xylose. Starches and refined sugars are hexoses which means the backbone of the sugar contains six carbon atoms. Most of the familiar sugars such as glucose and fructose are in this category. Nearly all biomass also includes sugars based on five carbon atoms, especially xylose. Pure xylose looks and tastes like ordinary sugar. However, typical yeasts do not ferment it to ethanol to any appreciable degree. Since the utilization of xylose represents a 20-40% increase in ethanol yield per ton of biomass, it is imperative to ferment this material to achieve good economy in most cases.

Several groups are trying to utilize xylose by genetically altering yeast. By taking genes from other organisms and adding them to the yeast, new metabolic pathways may be added. While this method has had some success, there are issues. The new pathways may disrupt the balance of the cell and not allow it to thrive in an industrial fermentation environment. For refineries that produce a co-product that is fed to animals (like most corn ethanol plants), there is also the issue of having a genetically modified organism in the food chain.

Trillium has chosen a different approach that does not require a genetically modified organism. Through the use of an industrial enzyme, xylose can be converted to xylulose. While xylose is not readily fermentable, xylulose is. The difficulty is that the conversion (called isomerization) happens at a different temperature and pH than the fermentation. By using an external reactor with an immobilized (fixed) enzyme, we have separated the two processes. That way, each can run at its own optimum.

To learn more about this process or how it can be used in your application, please contact us.