Trends in Brewing edition:11 location:Ghent date:13-17 April 2014
One of the main challenges in advanced 2nd generation bioethanol production is the search for and/or engineering of robust microorganisms able to also ferment pentose sugars next to hexoses present in the biomass hydrolysate as well as to cope with a variety of stressors such as osmo- and ethanol stress, and stress from chemical inhibitors present in the lignocellulosic hydrolysate. The aim of this work was to subject multi-tolerant Saccharomyces cerevisiae strains to fermentation experiments under conditions relevant for 2nd generation bioethanol.
2. Materials and Methods
A culture collection consisting of 370 S. cerevisiae strains isolated from various natural (e.g. soil, oak, cacao fermentation) and industrial habitats (e.g. beer, wine) was screened for osmo- and ethanol stress tolerance and inhibitor (HMF) tolerance. Subsequently, the 19 best performing strains were selected for bioethanol fermentation on an Eppendorf BioFlo310 bioreactor using (i) a high glucose concentration medium and (ii) a synthetic lignocellulotic hydrolysate medium containing HMF, furfural, acetic acid, formic acid, vannilinic acid and levulinic acid and compared with the performance of the industrial S. cerevisiae strain Ethanol Red.
Osmotolerant S. cerevisiae strains were found from various habitats such as beer, wine, oak, fruits and sugar products. The most ethanol tolerant strains were found in wine making. High HMF tolerance was mainly found among strains from natural habitats such as oak and cacao fermentation. Additionally, a few wine strains were found to perform well. A selection of these strains was subjected to bioethanol fermentation using the synthetic lignocellulosic medium. Results of these experiments will be presented in the poster.
4. What’s innovative
Mining natural and industrial habitats in search of promising S. cerevisiae strains for future bioethanol applications.
5. Practical relevance
Future bioethanol fermentation processes need specific ethanol producing strains in order to increase the efficiency of fermentation (e.g. very high gravity fermentation) or to cope with stressors which are related to fermentation of lignocellulosic material hydrolysates.