Fermentation of glucose and xylose in cattail processed by different pretreatment technologies

Abstract

The effects of different pretreatment technologies, including sulfuric acid, hot-water, NaOH, and MgCl2 pretreatments, on the fermentation of xylose and glucose to ethanol by Saccharomyces cerevisiae ATCC 24858 and Escherichia coli KO11 were investigated. In this study, cattail was used as the feedstock. The use of aquatic plant cattails to produce biofuel will add value to land and reduce emissions of greenhouse gases by replacing petroleum products. The pretreated biomass first was enzymatically hydrolyzed for 2 days, followed by a 2-day Simultaneous Saccharification and Fermentation (SSF) using S. cerevisiae. The glucose to ethanol yields were approximately 85 to 91% of the theoretical yield for this S. cerevisiae strain. Glucose and xylose released from cattail cellulose and hemicellulose could be fermented to ethanol using E. coli KO11, resulting in approximately 85% of the theoretical ethanol yield using either a Separate Hydrolysis and Fermentation (SHF) process or a SSF process. In order to improve the sugars to ethanol yields, a detoxification process is necessary to remove the inhibitory compounds produced during the acid pretreatment process. Among the four pretreatment methods, the dilute acid pretreatment was found to be superior, and additional research is required to optimize the economics of the overall biorefinery process.