Xu Guochao, Li Hao, Xing Wanru, Gong Lei, Dong Jinjun, Ni Ye
Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122 Jiangsu China.
Key Laboratory of Guangxi Biorefinery, Nanning, 530003 Guangxi China.
Biotechnol Biofuels. 2020 Oct 9;13:166. doi: 10.1186/s13068-020-01806-9. eCollection 2020.
Biobutanol is promising and renewable alternative to traditional fossil fuels and could be produced by 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.
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 could be reached. Consecutive batches for pretreatment of corncob were performed using gradiently decreased cellulase by 5 FPU g. At the end of the sixth batch, the concentration and specific yield of total sugars were 58.8 g L and 706 g kg pretreated corncob, saving a total of 50% cellulase. Utilizing hydrolysate as carbon source, butanol titer of 10.4 g L was achieved with butanol yield of 137 g kg pretreated corncob by DSM13864.
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.
生物丁醇是一种有前景的可再生传统化石燃料替代品，可由木质纤维素生物质的某些物种生产。然而，由于木质素层紧密堆积的结构，生物质难以水解成可发酵糖。开发用于增加表面积、去除半纤维素和木质素以及提高纤维素相对含量的预处理试剂和工艺是当前一个备受关注的领域。深共熔溶剂（DESs）是一类新型绿色溶剂，在木质纤维素生物质预处理中有效。然而，实现高糖浓度仍然具有挑战性，通常需要与其他试剂进行组合预处理。在本研究中，我们旨在开发在生物质预处理中具有高应用潜力且对生物丁醇发酵具有高生物相容性的新型DESs。
合成了几种以氯化甜菜碱和乙胺氯化物（EaCl）作为氢键受体的DESs。其中，以乳酸作为氢键供体的EaCl:LAC在玉米芯预处理中表现出最佳性能。仅通过用EaCl:LAC进行单次预处理，总糖含量可高达53.5 g/L。使用纤维素酶活性每克梯度降低5 FPU的条件对玉米芯进行连续批次预处理。在第六批结束时，总糖浓度和比产率分别为58.8 g/L和706 g/kg预处理玉米芯，共节省了50%的纤维素酶。利用水解产物作为碳源，DSM13864实现了10.4 g/L的丁醇滴度，丁醇产率为137 g/kg预处理玉米芯。
基于乙胺和乳酸的深共熔溶剂在高总糖浓度的玉米芯预处理中具有前景，并且与生物丁醇发酵兼容。本研究提供了一种高效的预处理试剂，用于轻松降低木质纤维素材料的顽固性，以及一种从可再生生物质进行生物丁醇发酵的有前景的工艺。
