Cellulosic ethanol fermentation development – the next steps towards commercial scale production using xylose fermenting yeast

Terranol has developed a robust and rapid xylose fermenting yeast (Saccharomyces cerevisiae) for commercial production of lignocellulosic ethanol. By up-regulation of the pentose phosphate pathway, and expression of a bacterial xylose isomerase, as well as a xylose 1-epimerase, the strain utilizes an efficient xylose metabolic pathway. All inserted genes are stably integrated in the genome of the yeast and the strain has undergone extensive evolutionary engineering, resulting in rapid xylose consumption, very low formation of xylitol, as well as high resistance towards biomass derived inhibitors.

Terranol’s strain has repeatedly achieved complete conversion of xylose and glucose in a short period of time in various lignocellulosic substrates in lab and pilot scale fermentations. Overall ethanol yields above 90% within 48 hours have been shown both in-house as well as at different partners. By moving from batch to controlled fed-batch fermentations, optimizing e.g. sugar concentrations and growth conditions, further improvement of ethanol yields, productivities and titers have been obtained. The next step for process development is to evaluate the possibilities of employing several consecutive fed-batches (draw and fill), and ultimately, continuous fermentation in a lignocellulosic ethanol production process.

Furthermore, we are now focusing on scaling up the process to demo and commercial scale together with our partners. This includes both fermentation scale up as well as propagation train development. The latest scientific results will be presented as well as an update on the strain’s progression towards commercial scale.