Facilely reducing recalcitrance of lignocellulosic biomass by a newly developed ethylamine-based deep eutectic solvent f
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Biotechnology for Biofuels Open Access
RESEARCH
Facilely reducing recalcitrance of lignocellulosic biomass by a newly developed ethylamine‑based deep eutectic solvent for biobutanol fermentation Guochao Xu1†, Hao Li1†, Wanru Xing1, Lei Gong1, Jinjun Dong1 and Ye Ni1,2*
Abstract Background: Biobutanol is promising and renewable alternative to traditional fossil fuels and could be produced by Clostridium species from lignocellulosic biomass. However, biomass is recalcitrant to be hydrolyzed into fermentable sugars attributed to the densely packed structure by layers of lignin. Development of pretreatment reagents and processes for increasing surface area, removing hemicellulose and lignin, and enhancing the relative content of cellulose is currently an area of great interest. Deep eutectic solvents (DESs), a new class of green solvents, are effective in the pretreatment of lignocellulosic biomass. However, it remains challenging to achieve high titers of total sugars and usually requires combinatorial pretreatment with other reagents. In this study, we aim to develop novel DESs with high application potential in biomass pretreatment and high biocompatibility for biobutanol fermentation. Results: Several DESs with betaine chloride and ethylamine chloride (EaCl) as hydrogen bond acceptors were synthesized. Among them, EaCl:LAC with lactic acid as hydrogen bond donor displayed the best performance in the pretreatment of corncob. Only by single pretreatment with EaCl:LAC, total sugars as high as 53.5 g L−1 could be reached. Consecutive batches for pretreatment of corncob were performed using gradiently decreased cellulase by 5 FPU g−1. At the end of the sixth batch, the concentration and specific yield of total sugars were 58.8 g L−1 and 706 g kg−1 pretreated corncob, saving a total of 50% cellulase. Utilizing hydrolysate as carbon source, butanol titer of 10.4 g L−1 was achieved with butanol yield of 137 g kg−1 pretreated corncob by Clostridium saccharobutylicum DSM13864. Conclusions: Ethylamine and lactic acid-based deep eutectic solvent is promising in pretreatment of corncob with high total sugar concentrations and compatible for biobutanol fermentation. This study provides an efficient pretreatment reagent for facilely reducing recalcitrance of lignocellulosic materials and a promising process for biobutanol fermentation from renewable biomass. Keywords: Deep eutectic solvent, Lignocellulosic biomass, Ethylamine, Pretreatment, Biobutanol
*Correspondence: [email protected] † Guochao Xu and Hao Li contributed equally to this work 1 Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China Full list of author information is available at the end of the article
Background Biofuels are promising, renewable and natural alternatives to traditional fossil fuels and have gained great interest [1]. Among them, biobutanol possesses great potential due to its high hydrophobicity, high energy density, low corrosiveness and more compatibi
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