Yeast adaption on the substrate straw

The process for bioethanol production of lignocellulosics (e.g. straw) requires among other issues investigation concerning an ideal yeast strain for the fermentation process. Hence various yeast strains were adapted by special growth conditions and systematic selection. To improve the utilization of C5-sugars (e.g. xylose), yeast strains have been cultivated on xylose-minimal agar. For enhanced resistance against inhibitory compounds released from straw in the hydrolysation and pretreatment process, several yeast strains have been adapted in wheat straw hydrolysate medium. To raise the limited thermo- and osmotolerance of some strains, they have been grown at increased temperatures as well as with enhanced ethanol and sugar concentrations. The ethanol production of yeasts adapted to xylose could be raised considerably. Thermal adaption to 40 °C could be reached. A significant increase of inhibitor tolerance could be observed. Strains tolerant to 12 % vol. ethanol were generated.