Bioethanol Production from Dilute-acid Pre-treated Wheat Straw Liquor Hydrolysate by Genetically Engineered Saccharomyces cerevisiae

N. Marđetko, M. Novak, A. Trontel, M. Grubišić, M. Galić and B. Šantek

Abstract
Sustainable recycling of lignocellulosic biomass includes utilization of all carbohydrates present in its hydrolysates. Since wheat straw is a xylose-rich raw material, utilization of xylose from obtained liquid part (liquor) of hydrolysates improves overall bioprocess efficiency. In this work, dilute acid pre-treatment of wheat straw was performed in high-pressure reactor at different temperatures (160 °C – 200 °C), residence times (1 min – 10 min), and acids (H2SO4 and H3PO4) concentrations. During dilute acid pre-treatment, hemicellulose is degraded to pentose sugars that cannot be used by industrial ethanol-producing yeasts. Therefore, genetically engineered Saccharomyces cerevisiae strain that can utilize xylose was used. Fermentations were performed on different xylose-rich liquor wheat straw hydrolysates in shake-flasks and in horizontal rotating tubular bioreactor. The efficiency of fermentations carried out in shake flasks using xylose-rich liquor wheat straw hydrolysates were in the range of 19.61 – 74.51 %. However, the maximum bioprocess efficiency (88.24 %) was observed during fermentation in the HRTB on the liquor wheat straw hydrolysate obtained by pre-treatment with 2 % w/w phosphoric acid. (This work is licensed under a Creative Commons Attribution 4.0 International License.)

This work is licensed under a Creative Commons Attribution 4.0 International License

Keywords
dilute acid pre-treatment, high-pressure reactor, wheat straw, xylose utilisation, bioethanol, genetically engineered Saccharomyces cerevisiae