Location: Crop Bioprotection Research
Title: In Situ Detoxification of Fermentation Inhibitors by Stress Tolerant Ethanologenic Yeast for Low-Cost Biomass Conversion to Ethanol Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2006
Publication Date: May 30, 2006
Citation: Liu, Z., Slininger, P.J. 2006. In situ detoxification of fermentation inhibitors by stress tolerant ethanologenic yeast for low-cost biomass conversion to ethanol [abstract]. World Bio-Energy 2006 Proceedings. p. 121. Technical Abstract: Biomass pretreatment using economic dilute acid hydrolysis generates furfural and 5-hydroxymethylfurfural (HMF) which inhibit yeast growth and fermentation. Remediation of the inhibitors increases cost and wastes for bioethanol production. The objectives of this study were to understand mechanism of stress tolerance involved in biomass conversion inhibitors such as furfural and HMF, and to develop more tolerant ethanologenic yeast for cost-competitive bioethanol production. We aim to develop tolerant strains that withstand inhibitors furfural and HMF, and produce ethanol without additional detoxification procedures. Using functional genomics approaches, we investigate transcriptome and metabolic profiling for ethanologenic yeast under the inhibitor challenged conditions. Genomic expression response of the yeast to individual and combined inhibitors over a time course study for ethanol fermentation was examined using DNA oligonucleotide microarray and real-time quantitative RT-PCR. We developed ethanologenic yeast more tolerant to furfural and HMF, each individually or in combination, under simulated laboratory conditions. These strains showed significantly enhanced biotransformation to convert furfural into furfural alcohol and HMF into 2,5-bis-hydroxymethylfuran (furan-2,5-di-methanol, FDM) and produce a normal yield of ethanol. The transformation dynamics of furfural and HMF was completed and ethanol produced in 48 h for a tolerant strain. In contrast, a normal control strain was unable to grow and establish a culture in the present of the inhibitors at 48 h. The tolerant strains showed distinctive genomic expression patterns to cope with the inhibitor stress immediately after the cells were exposed to the inhibitory stress condition. Our study suggests that it is possible to in situ detoxify inhibitors generated by economic dilute acid hydrolysis pretreatment for cost-competitive bioethanol conversion.