Impact of Pretreatment Technologies on Saccharification and Isopentenol Fermentation of Mixed Lignocellulosic Feedstocks

Jian Shi, Kevin W. George, Ning Sun, Wei He, Chenlin Li, Vitalie Stavila, Jay D. Keasling, Blake A. Simmons, Taek Soon Lee, Seema Singh

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

In order to enable the large-scale production of biofuels or chemicals from lignocellulosic biomass, a consistent and affordable year-round supply of lignocellulosic feedstocks is essential. Feedstock blending and/or densification offers one promising solution to overcome current challenges on biomass supply, i.e., low energy and bulk densities and significant compositional variations. Therefore, it is imperative to develop conversion technologies that can process mixed pelleted biomass feedstocks with minimal negative impact in terms of overall performance of the relevant biorefinery unit operations: pretreatment, fermentable sugar production, and fuel titers. We processed the mixture of four feedstocks—corn stover, switchgrass, lodgepole pine, and eucalyptus (1:1:1:1 on dry weight basis)—in flour and pellet form using ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate, dilute sulfuric acid (DA), and soaking in aqueous ammonia (SAA) pretreatments. Commercial enzyme mixtures, including cellulases and hemicellulases, were then applied to these pretreated feedstocks at low to moderate enzyme loadings to determine hydrolysis efficiency. Results show significant variations on the chemical composition, crystallinity, and enzymatic digestibility of the pretreated feedstocks across the different pretreatment technologies studied. The advanced biofuel isopentenol was produced during simultaneous saccharification and fermentation (SSF) of pretreated feedstocks using an engineered Escherichia coli strain. Results show that IL pretreatment liberates the most sugar during enzymatic saccharification, and in turn led to the highest isopentenol titer as compared to DA and SAA pretreatments. This study provides insights on developing biorefinery technologies that produce advanced biofuels based on mixed feedstock streams.

Original languageEnglish
Pages (from-to)1004-1013
Number of pages10
JournalBioenergy Research
Volume8
Issue number3
DOIs
StatePublished - Sep 8 2015

Bibliographical note

Funding Information:
This work conducted by the Joint BioEnergy Institute was supported by the Office of Science, Office of Biological and Environmental Research, of the US Department of Energy under Contract No. DE-AC02-05CH11231. ABPDU acknowledges the funding support from Office of Biomass Program within the US DOE’s Office of Energy Efficiency and Renewable Energy, and also the funding support from the American Recovery and Reinvestment Act. We acknowledge Vicki S. Thompson and Neal A. Yancey from Idaho National Laboratory for providing biomass feedstocks and Sonny Zhang for lab assistance. We thank Novozymes for the gift of the enzyme mixtures used in this study.

Publisher Copyright:
© 2015, Springer Science+Business Media New York (outside the USA).

Keywords

  • Biomass pellet
  • Biomass pretreatment
  • Dilute acid
  • Ionic liquid
  • Isopentenol
  • Mixed feedstock
  • Simultaneous saccharification and fermentation
  • Soaking aqueous ammonia

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Agronomy and Crop Science
  • Energy (miscellaneous)

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