TY - JOUR
T1 - Reducing agents assisted fed-batch fermentation to enhance ABE yields
AU - Chandgude, Vijaya
AU - Välisalmi, Teemu
AU - Linnekoski, Juha
AU - Granström, Tom
AU - Pratto, Bruna
AU - Eerikäinen, Tero
AU - Jurgens, German
AU - Bankar, Sandip
N1 - Funding Information:
The authors are grateful to the Aalto School of Chemical Engineering and the Finnish Cultural Foundation for the financial support of this study. We acknowledge experimental help from Lauri Honkanen and analysis help from Esa Uosukainen. We thank Riikka Särkelä, Ville Aumala, Sami Havukainen, and He Li for helpful suggestions. We also acknowledge Nahla Osmanbegovic for useful comments on the manuscript. Aalto University Bioeconomy infrastructure is acknowledged.
PY - 2021/1/1
Y1 - 2021/1/1
N2 - 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.
AB - 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.
KW - ABE fermentation
KW - Butanol dehydrogenase
KW - Clostridium acetobutylicum
KW - Fed-batch
KW - NADH
KW - Reducing agents
UR - http://www.scopus.com/inward/record.url?scp=85096713627&partnerID=8YFLogxK
U2 - 10.1016/j.enconman.2020.113627
DO - 10.1016/j.enconman.2020.113627
M3 - Article
AN - SCOPUS:85096713627
SN - 0196-8904
VL - 227
JO - Energy Conversion and Management
JF - Energy Conversion and Management
M1 - 113627
ER -