Reducing agents assisted fed-batch fermentation to enhance ABE yields

Vijaya Chandgude, Teemu Välisalmi, Juha Linnekoski, Tom Granström, Bruna Pratto, Tero Eerikäinen, German Jurgens, Sandip Bankar*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Acetone-butanol-ethanol (ABE) fermentation process is a promising bioenergy option amid rising concerns over the environmental impact of fossil fuel usage. However, the commercialization of the ABE process has been marred by challenges of low product yield and titer, thereby non-competitive process economics. Here, we coupled cost competitive reducing agents with a controlled feeding strategy to improve both product titer and yield. Reducing agents promote cofactor dependent butanol production, while fed-batch operation enhances glucose consumption, final ABE titer, and partly mitigates product toxicity. The effects of ascorbic acid, L- cysteine, and dithiothreitol (DTT) on ABE fed-batch production using Clostridium acetobutylicum was investigated
in current study. NADH, ATP, extracellular amino acid secretion, and NADH-dependent butanol dehydrogenase (BDH) assays were performed to study the metabolic modifications triggered by reducing agents. Incidentally, L-
cysteine and DTT improved ABE solvent titer by 2-fold, producing 24.33 and 22.98 g/L ABE with solvent yields of 0.38 and 0.37 g/g, respectively. Elevated NADH, BDH, and ATP levels in fermentation broth reflected in enhanced ABE titer and yield. Furthermore, histidine secretion emerged as an important factor in Clostridial acid stress tolerance in this study. The results demonstrate that addition of reducing agents in fed-batch ABE fermentation operation enables efficient utilization of glucose with significant improvement in solvent production.
Original languageEnglish
Article number113627
Number of pages11
JournalEnergy Conversion & Management
Volume227
DOIs
Publication statusPublished - 1 Jan 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • ABE fermentation
  • butanol dehydrogenase
  • Clostridium acetobutylicum
  • fed-batch
  • NADH
  • reducing agents

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