低共熔溶剂和次氯酸钠组合预处理秸秆及在丁醇发酵中的应用

Combinatorial pretreatment of straw with DES and sodium hypochlorite and its application in butanol fermentation

随着传统化石能源日趋枯竭,木质纤维素生物质等可再生资源的综合利用得到越来越多的关注。为了更好地利用木质纤维素生物质,采用物理、化学或生物方法降低其结构顽抗性是必不可少的步骤。在前期研究中,本文作者所在实验室发现了一种乙胺盐酸盐为氢键受体、乳酸为氢键供体的新型低共熔溶剂(EaCl∶LAC),其对玉米芯有很好的去除半纤维素的作用。本文将EaCl∶LAC用于预处理水稻秸秆,并结合碱性氧化剂NaClO,进一步提高了木质素的去除率。在最优条件下,经EaCl∶LAC/NaClO预处理后水稻秸秆的半纤维素和木质素的去除率分别为94.9%和80.2%。将预处理后水稻稻秆经纤维素酶解可得到总还原糖浓度为60.46g/L的秸秆水解液。采用梭菌Clostridium saccharobutylicum DSM13864利用稻秆水解液进行丁醇发酵,72h后丁醇浓度为10.16g/L,丁醇的糖醇产率为0.22g/g(total sugar)。本文提供了一种提高木质纤维素生物质酶解效率和水解液还原糖浓度的方法,无需外源添加葡萄糖和脱毒处理,可直接用于发酵合成生物丁醇。

With depletion of traditional fossil energies,comprehensive utilization of renewable resources such as lignocellulosic biomass has received increasing attention.For efficient utilization of lignocellulosic biomass,reducing structural recalcitrance of lignocellulosic biomass by physical,chemical or biological methods is a prerequisite.In our previous study,a new deep eutectic solvent(EaCl∶LAC)was developed with ethylamine hydrochloride as hydrogen bond acceptor and lactic acid as hydrogen bond donor.EaCl∶LAC is efficient in removing the hemicellulose from corncob.In this study,EaCl∶LAC was combined with a basic oxidant NaClO for the pretreatment of rice straw,resulting elevated hemicellulose and lignin removal percentages.After optimization,total reducing sugars in rice straw hydrolysate pretreated by EaCl∶LAC/NaClO was increased to 60.46g/L,with hemicellulose removal of 94.9%and delignification of 80.2%.Furthermore,rice straw hydrolysate was utilized for biobutanol fermentation by Clostridium saccharobutylicum DSM13864,achieving butanol titer of 10.16g/Land productivity of 0.22g/gtotal sugar after 72 hours.This study provides a promising and effective method for pretreatment of lignocellulosic biomass,which can be facilely used in biofuel fermentation without external sugar and detoxification.