Challenges in enzymatic hydrolysis and fermentation of pretreated Arundo donax revealed by a comparison between SHF and SSF

Magnus Ask, Kim Olofsson, Tommaso Di Felice, Laura Ruohonen, Merja Penttilä, Gunnar Lidén, Lisbeth Olsson (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

57 Citations (Scopus)

Abstract

The perennial herbaceous crop Arundo donax is a potential feedstock for second-generation bioethanol production. In the present work, two different process options were investigated for the conversion of two differently steam-pretreated batches of A. donax. The pretreated raw material was converted to ethanol with a xylose-consuming Saccharomyces cerevisiae strain, VTT C-10880, by applying either separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF). The highest overall ethanol yield and final ethanol concentration were achieved using SHF (0.27 g g-1 and 20.6 g L-1 compared to 0.24 g g-1 and 19.0 g L -1 when SSF was used). The performance of both SHF and SSF was improved by complementing the cellulolytic enzymes with hemicellulases. The higher amount of acetic acid in one of the batches was shown to strongly affect xylose consumption in the fermentation. Only half of the xylose was consumed when batch 1 (high acetic acid) was fermented, compared to that 94% of the xylose was consumed in fermentation of batch 2 (lower acetic acid). Furthermore, the high amount of xylooligomers present in the pretreated materials considerably inhibited the enzymatic hydrolysis. Both the formation of xylooligomers and acetic acid thus need to be considered in the pretreatment process in order to achieve efficient conversion of A. donax to ethanol.

Original languageEnglish
Pages (from-to)1452-1459
JournalProcess Biochemistry
Volume47
Issue number10
DOIs
Publication statusPublished - 1 Oct 2012
MoE publication typeA1 Journal article-refereed

Keywords

  • Acetic acid stress
  • Arundo donax
  • Giant reed
  • SHF
  • SSF
  • Xylooligomers

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