摘要
尽管目前纤维原料酶解转化乙醇研究已取得较大进展,但是仍需利用各种技术降低转化成本以实现其商业化生产。如:采用有效的预处理方法以改变纤维原料高度复杂的内部结构;降低生物转化过程中所需化学品的用量和能耗;实现在低酶用量下纤维原料向目标产物的高效转化等。笔者从添加表面活性剂的角度讨论了对纤维原料酶解转化的影响。在纤维酶解转化过程中添加表面活性剂能够降低木质素对酶解的抑制作用,增强纤维素的可及度,改善底物的润湿性和降低反应体系界面张力,从而提高酶解效率、降低纤维素酶用量,实现纤维原料向目标产物的高效转化。综述了合成表面活性剂、天然表面活性剂和生物表面活性剂等种类及其性质,以及不同类型表面活性剂在纤维原料酶解转化中的应用,并从对纤维原料底物性质、纤维素酶及酶解体系的影响等方面,总结比较了表面活性剂在纤维酶解转化过程中的促进作用及机理。充分利用富含天然皂苷的农林废弃物或木质素磺酸盐等工业废弃物辅助纤维原料酶解转化,具有重要的环保意义和经济效益。
At present,although great progress has been made on the conversion of cellulosic ethanol,the high cost of the conversion still needs to be improved to achieve its commercial production.The highly complex internal structure of fibrous materials could be changed by effective pretreatment.Reducing the amount of chemicals and energy consumption is required in the bioconversion process.High efficiency conversion of cellulose fiber to target products at low enzyme consumption is highly desired.The effect of adding surfactant on enzymatic hydrolysis of cellulose raw materials was discussed in this review.Adding surfactant to the fermentation system is beneficial for improving the enzymatic hydrolysis of lignocellulose and reducing the amount of cellulase by decreasing non-productive enzyme adsorption onto lignin,thus enhancing the susceptibility of the substrate to the enzyme,improving the wettability of the lignocellulosic substrate,and reducing the surface tension of the reaction system.Surfactants are amphiphilic molecules composed of non-polar hydrocarbon chains and polar or ionic groups,which can reduce the surface tension of substrate to prevent aggregation and forming micelles as well as improve the wetting,emulsifying,and dispersing ability of the substrate.Surfactants can be divided into ionic and nonionic according to whether the hydrophilic groups are charged,or oil soluble and water soluble surfactant according to the solubility,or chemical synthetic surfactants,natural surfactants,and biological surfactants according to their orgin source.Natural surfactants mainly include saponin surfactant,phospholipid surfactant,amino acid surfactant,and saccharide surfactant.Biological surfactants include glycolipids,lipopeptides,phospholipids,polysaccharide protein complexes,and fatty acid neutral lipids according to their structures.This review aims to present an overview of the research progress on surfactants-assisted ethanol production processes with different types of surfactants(synthetic surfactant,natural surfactant,and biosurfactant).The possible mechanism on how surfactants can enhance the bioconversion of lignocellulosic biomass to bioethanol was also explored.Surfactants can reduce the interfacial tension of enzymatic hydrolysis system,which promote the dissolution of cellulase.The addition of surfactant can significantly reduce the contact angle of the substrate,thus effectively improving the wettability of the substrate and promoting the enzymatic hydrolysis of lignocellulosic materials.Lignosulfonate,an anionic surfactant,can be combined with proteins having opposite charge in cellulase to form a lignosulfonate-cellulase complex,which can reduce the ineffective adsorption of lignin on enzyme.Making full use of natural saponin surfactants from agricultural and forestry wastes or lignosulfonate and other industrial wastes to assist the production of cellulosic ethanol has both economic and environmental benefits.
作者
蒋建新
郑天然
冯月
薛雯雯
邢杨
JIANG Jianxin;ZHENG Tianran;FENG Yue;XUE Wenwen;XING Yang(College of Materials Science and Technology,MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy,Beijing Forestry University,Beijing 100083,China)
出处
《林业工程学报》
CSCD
北大核心
2019年第4期12-21,共10页
Journal of Forestry Engineering
基金
国家自然科学基金(31070510)
广西林产化学与工程重点实验室开放课题(GXFC16-01)
关键词
表面活性剂
纤维原料
纤维素酶
酶解
纤维乙醇
surfactant
lignocellulose
cellulase
enzymatic hydrolysis
fiber ethanol
