微波预处理玉米秸秆的工艺研究
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摘要
木质纤维素是地球上最丰富、最廉价的可再生资源,被认为是最重要的燃料酒精生产的后续资源物质。目前利用木质纤维素生产燃料酒精的技术原理和工艺路线虽已被认知,但由于成本过高,导致纤维素酒精的价格尚无法与粮食酒精相竞争,开发新型低成本的燃料酒精生产技术已成为全世界共识。预处理方法和工艺是纤维素类生物质制取燃料酒精的关键步骤之一,其成本占据整个工艺的30%以上,而现有的各种方法都由于成本过高、能耗过大一直没有得到推广应用。因此开发经济适用、效果好的预处理方法对生物质制取燃料酒精具有重要意义。
本论文根据微波加热的基本原理,结合预处理的目标和特点,将其引入秸秆的预处理过程,对不同的吸波介质进行了比较和选择,并对该吸波介质下微波预处理的各项参数进行了优化。主要研究内容如下:
1、吸波介质的选择:分别以HCl、H2SO4、NaOH、H2O、NH3H2O为吸波介质,比较不同吸波介质下微波预处理的效果,通过对处理后秸秆的成分变化、酶解液还原糖含量以及对纤维素酶毒性的分析,确定水是对纤维素酶毒性最小、预处理效果较好且环保经济的吸波介质。
2、微波水预处理条件的优化:将秸秆分别在不同的液固比、不同的微波功率下处理不同时间后,分析其成分变化并对预处理过的秸秆进行酶水解和等温同时糖化(SSF),通过比较酶解后的单糖转化率和SSF乙醇产率得到微波水预处理的最优条件:以1g秸秆为底物,按照40:1的液固比加入水,在800W的微波下加热4min。以该条件下预处理的秸秆作底物,用纤维素酶水解和SSF时,获得49.1%的葡萄糖转化率,21.1%的木糖转化率和76%的理论乙醇产率。
3、微波预处理的机理分析:应用原子力显微镜(AFM)观察微波水预处理前后的秸秆表面形貌,发现未经处理的秸秆表面光滑、平整,纤维丝排列致密,而经微波预处理后的秸秆表面有很多微孔。结合本研究中预处理前后秸秆成分的变化结果,发现微波水预处理与传统的预处理方法原理不一样:传统的预处理方法都是通过纤维素与半纤维素或木质素的分离使秸秆致密的结构变得松散,从而提高底物的可消化性;而微波预处理是利用水分子在秸秆表面“钻孔”从而增大秸秆与纤维素酶的接触面积,也使得纤维素酶容易进入秸秆内部进行水解从而达到提高酶解效率的目的。
本论文首次对微波水预处理的工艺进行了优化研究,并通过AFM首次直接观察到了微波对秸秆形貌的影响,对微波预处理的机理进行了深入分析,这些基础研究将为木质纤维素制取燃料酒精的应用提供重要价值。
The lignocellulose is the most abundant and cheapest renewable resources on the earth, and is supposed to be the most important successive resources for fuel alcohol production. Till now, the technology theory and process are investigated and cognized by researchers, but the cellulose fuel alcohol can not competed with food alcohol since the high cost of cellulose. Therefore, it has been a worldly focus to develop a new, low cost production technology for fuel alcohol production. Pretreatment is among the most costly steps, which takes up up to more than thirty percent of the whole cost and has a major influence on both prior and subsequent operations. Although several pretreatments are promising, they are still confined in laboratory because of huge energy consumed during the process. So developing a cheap and practicable pretreatment has profound meaning on biomass fuel project.
Based on mechanism of microwave hydrogenation, microwave is introduced into corn stover pretreatment. Aimed at a good digestibility of the pretreated solids, several microwave absorbers were used and compared and microwave pretreatment were optimized under a microwave absorber selected. The main contents run as follows:
Effect of HCl, H2SO4, NaOH, H2O, NH3H2O on microwave pretreatment was studied. The contents of lignin, cellulose and hemicellulose before and after pretreatment were measured by acid hydrolysis method. Reducing sugars after pretreatment combined with enzyme hydrolysis were tested by DNS method. According to the test results, water is determined to be the best microwave absorber in pretreatment.
Microwave and water pretreatment is applied and optimized. The contents of lignin, cellulose and hemicellulose before and after pretreatment were measured by acid hydrolysis method. Glucose and xylose after pretreatment combined with enzyme hydrolysis is tested by HPLC. Ethanol after pretreatment combined with SSF is tested by GC. According to the test results, the optimal conditions were achieved, that is soaking 1g dry corn stover in 40mL water, then heated under 800W of microwave power for 4min. At the optimal conditions, 49.1% of cellulose was hydrolyzed to glucose and 21.1% of hemicellulose was converted to xylose. When the resulting pretreated solids at the optimal conditions was SSF, ethanol was achieved at 88% of theoretical yield.
It can be clearly seen that un-retreated stover has a smooth and flat exterior with micro fibrils tight arrayed, while pretreated ones have a lot of micro pores on the surface. Considering the results having achieved in this paper, it is discovered that microwave pretreatment is obviously different from other known pretreatment technologies in mechanism. Almost all of the leading pretreatment technologies advanced digestibility of the solids through removal of hemicellulose or lignin, which leads to a relatively incompact structure. Microwave pretreatment enlarged the interface between solids and enzyme due to the micro pores water molecule drilled, which also facilitates enzyme entrance into interiors of solids.
In this paper, microwave and water pretreatment was first applied and optimized. Micro pores on stover surface caused by microwave and water molecule was direct observed for the first time, based on which, the mechanism of microwave pretreatment was analyzed in particular. All these basic researches will have a significant value on application of lignocelluloses fuel alcohol production.
本论文根据微波加热的基本原理,结合预处理的目标和特点,将其引入秸秆的预处理过程,对不同的吸波介质进行了比较和选择,并对该吸波介质下微波预处理的各项参数进行了优化。主要研究内容如下:
1、吸波介质的选择:分别以HCl、H2SO4、NaOH、H2O、NH3H2O为吸波介质,比较不同吸波介质下微波预处理的效果,通过对处理后秸秆的成分变化、酶解液还原糖含量以及对纤维素酶毒性的分析,确定水是对纤维素酶毒性最小、预处理效果较好且环保经济的吸波介质。
2、微波水预处理条件的优化:将秸秆分别在不同的液固比、不同的微波功率下处理不同时间后,分析其成分变化并对预处理过的秸秆进行酶水解和等温同时糖化(SSF),通过比较酶解后的单糖转化率和SSF乙醇产率得到微波水预处理的最优条件:以1g秸秆为底物,按照40:1的液固比加入水,在800W的微波下加热4min。以该条件下预处理的秸秆作底物,用纤维素酶水解和SSF时,获得49.1%的葡萄糖转化率,21.1%的木糖转化率和76%的理论乙醇产率。
3、微波预处理的机理分析:应用原子力显微镜(AFM)观察微波水预处理前后的秸秆表面形貌,发现未经处理的秸秆表面光滑、平整,纤维丝排列致密,而经微波预处理后的秸秆表面有很多微孔。结合本研究中预处理前后秸秆成分的变化结果,发现微波水预处理与传统的预处理方法原理不一样:传统的预处理方法都是通过纤维素与半纤维素或木质素的分离使秸秆致密的结构变得松散,从而提高底物的可消化性;而微波预处理是利用水分子在秸秆表面“钻孔”从而增大秸秆与纤维素酶的接触面积,也使得纤维素酶容易进入秸秆内部进行水解从而达到提高酶解效率的目的。
本论文首次对微波水预处理的工艺进行了优化研究,并通过AFM首次直接观察到了微波对秸秆形貌的影响,对微波预处理的机理进行了深入分析,这些基础研究将为木质纤维素制取燃料酒精的应用提供重要价值。
The lignocellulose is the most abundant and cheapest renewable resources on the earth, and is supposed to be the most important successive resources for fuel alcohol production. Till now, the technology theory and process are investigated and cognized by researchers, but the cellulose fuel alcohol can not competed with food alcohol since the high cost of cellulose. Therefore, it has been a worldly focus to develop a new, low cost production technology for fuel alcohol production. Pretreatment is among the most costly steps, which takes up up to more than thirty percent of the whole cost and has a major influence on both prior and subsequent operations. Although several pretreatments are promising, they are still confined in laboratory because of huge energy consumed during the process. So developing a cheap and practicable pretreatment has profound meaning on biomass fuel project.
Based on mechanism of microwave hydrogenation, microwave is introduced into corn stover pretreatment. Aimed at a good digestibility of the pretreated solids, several microwave absorbers were used and compared and microwave pretreatment were optimized under a microwave absorber selected. The main contents run as follows:
Effect of HCl, H2SO4, NaOH, H2O, NH3H2O on microwave pretreatment was studied. The contents of lignin, cellulose and hemicellulose before and after pretreatment were measured by acid hydrolysis method. Reducing sugars after pretreatment combined with enzyme hydrolysis were tested by DNS method. According to the test results, water is determined to be the best microwave absorber in pretreatment.
Microwave and water pretreatment is applied and optimized. The contents of lignin, cellulose and hemicellulose before and after pretreatment were measured by acid hydrolysis method. Glucose and xylose after pretreatment combined with enzyme hydrolysis is tested by HPLC. Ethanol after pretreatment combined with SSF is tested by GC. According to the test results, the optimal conditions were achieved, that is soaking 1g dry corn stover in 40mL water, then heated under 800W of microwave power for 4min. At the optimal conditions, 49.1% of cellulose was hydrolyzed to glucose and 21.1% of hemicellulose was converted to xylose. When the resulting pretreated solids at the optimal conditions was SSF, ethanol was achieved at 88% of theoretical yield.
It can be clearly seen that un-retreated stover has a smooth and flat exterior with micro fibrils tight arrayed, while pretreated ones have a lot of micro pores on the surface. Considering the results having achieved in this paper, it is discovered that microwave pretreatment is obviously different from other known pretreatment technologies in mechanism. Almost all of the leading pretreatment technologies advanced digestibility of the solids through removal of hemicellulose or lignin, which leads to a relatively incompact structure. Microwave pretreatment enlarged the interface between solids and enzyme due to the micro pores water molecule drilled, which also facilitates enzyme entrance into interiors of solids.
In this paper, microwave and water pretreatment was first applied and optimized. Micro pores on stover surface caused by microwave and water molecule was direct observed for the first time, based on which, the mechanism of microwave pretreatment was analyzed in particular. All these basic researches will have a significant value on application of lignocelluloses fuel alcohol production.
引文
1辛维.作物秸秆的微生物转化与利用.山东大学理学硕士学位论文.2005:2~20
2朱圣东.微波技术用于植物纤维素原料生产酒精的研究.2005:3~60
3 Nathan Mosier. Optimization of pH controlled liquid hot water pretreatment of corn stover. Bioresource Technology. 2005,96: 1986~1993
4 Chaogang Liu, Charles E. Wyman. Partial flow of compressed-hot water through corn stover to enhance hemicellulose sugar recovery and enzymatic digestibility of cellulose.Bioresource Technology. 2005, 96: 1978~1985
5 Badal C. Saha, Loren B. Iten, Michael A. Cotta, Y. Victor Wu. Dilute acid pretreatment, enzymatic saccharification and fermentation of wheat straw to ethanol. Process Biochemistry. 2005, 40: 3693~3700
6 Tae Hyun Kim, Yoon Y. Lee. Pretreatment and fractionation of corn stover by ammonia recycle percolation process. Bioresource Technology. 2005, 96: 2007~2013
7 Sehoon Kim, Mark T. Holtzapple. Lime pretreatment and enzymatic hydrolysis of corn stover.Bioresource Technology. 2005, 96: 1994~2006
8杨伯伦,贺拥军.微波加热在化学反应中的应用进展.现代化工. 2001,21(4): 8~13
9王继业,许赤兵,宋会花等.微波加热在无机固相反应中的应用.河北师范大学学报(自然科学版). 2004,28(4):396~400
10贾艳宗,马沛生,王彦飞.微波在酯化和水解反应中的应用.化工进展. 2004,23(6):641~645
11胡同亮,李萍,张起凯等.微波辐射法原油脱水的研究.炼油技术与工程. 2003,33(2):6~8
12王金成,熊力.微波在环境化学中的应用.气象水文海洋仪器. 2001, (2):44~49
13杨强.微波技术在环境保护中的应用.环境保护. 2001,1:41~43
14李冬梅.玉米秸秆制取燃料酒精的细菌筛选及工艺研究.哈尔滨工业大学理学硕士学位论文.2005:25~50
15 Charles E. Wyman, Bruce E. Dale, Richard T. Elander. Comparative sugarrecovery data from laboratory scale application of leading pretreatment technologies to corn stover. Bioresource Technology. 2005, 96: 2026~2032
16安宏.纤维素水解制取燃料酒精的试验研究.浙江大学硕士学位论文.2005:5~32
17 Farzaneh Teymouri, Lizbeth Laureano-Perez, Hasan Alizadeh, Bruce E.Dale. Optimization of the ammonia fiber explosion (AFEX) treatment parameters for enzymatic hydrolysis of corn stover. Bioresource Technology. 2005, 96: 2014~2018
18 Tae Hyun Kim, Y.Y. Lee. Fractionation of corn stover by hot-water and aqueous ammonia treatment. Bioresource Technology. 2006, 97: 224~232
19 Badal C. Saha, Loren B. Iten, Michael A. Cotta, Y. Victor Wu. Dilute acid pretreatment, enzymatic saccharification and fermentation of wheat straw to ethanol. Biomass and Bioenergy. 2005, 28: 411~417
20 Hongzhang Chen, Liying Liu, Xuexia Yang, Zuohu Li. New process of maize stalk amination treatment by steam explosion. Biomass and Bioenergy. 2005, 28: 411~417
21 Todd A. Lloyd, Charles E. Wyman. Combined sugar yields for dilute sulfuric acid pretreatment of corn stover followed by enzymatic hydrolysis of the remaining solids. Bioresource Technology. 2005, 96: 1959~1966
22 Ye Sun, Jay J. Cheng. Dilute acid pretreatment of rye straw and bermudagrass for ethanol production. Bioresource Technology. 2005, 96: 1599~1606
23 Todd A. Lloyd, Charles E. Wyman. Combined sugar yields for dilute sulfuric acid pretreatment of corn stover followed by enzymatic hydrolysis of the remaining solids. Bioresource Technology. 2005, 96: 1967~1977
24 N. Rao Lakkakula, Marybeth Lima, Terry Walker. Rice bran stabilization and rice bran oil extraction using ohmic heating q. Bioresource Technology. 2004, 92: 157~161
25 Beatriz Palmarola-Adrados. Pretreatment of barley husk for bioethanol production. Journal of Chemical Technology and Biotechnology. 2005, 80: 85~91
26 A. Domnguez, J.A. Menendez. Production of bio-fuels by high temperature pyrolysis ofsewage sludge using conventional and microwaveheating.Bioresource Technology. 2006, 97: 1185~1193
27 B. Palmarola Adrados. Size exclusion behavior of hydroxypropylcellulose beads with temperature-dependent porosity. Journal of Chromatography A. 2001, 930: 73~78
28 Shengdong Zhu, Yuanxin Wu. The effect of microwave irradiation on enzymatic hydrolysis of rice straw. Bioresource Technology. 2006, 97: 1964~1968
29 Klaus Fischer. Generation of organic acids and monosaccharides by hydrolytic and oxidative transformation of food processing residues. Bioresource Technology. 2005, 96: 831~842
30 A. Kaminskal, M. Sawczak. The effect of wavelength and fluence on the cellulose degradation of laser-cleaned paper. Laser Physics and Applications: 382~386
31 Meijuan Zeng, Nathan S. Mosier. Microscopic Examination of Changes of Plant Cell Structure in Corn Stover Due to Hot Water Pretreatment and Enzymatic Hydrolysis: 265~277
32黄宇彤.世界燃料酒精生产形势.酿酒. 2001, 28(5): 12~15
33刘洪凤.秸秆纤维性能.东华大学学报. 2002, 2(28): 123~127
34孙健.纤维素原料生产燃料酒精的技术现状.可再生能源. 2003, 6(2): 5~9.
35卢雪梅,马登波,高培基.纤维素酶活的测定.纤维素科学与技术. 1994, 2(4): 24
36李佐虎,岑沛霖.纤维素酒精的分散、耦合、并行系统.生物技术通报. 1999, 4: 27~29
37刘家健,陆怡.预处理对纤维素酶降解影响的研究.林产化学与工业. 1995, 15(3): 67~71
38熊键.微波对纤维素Ⅰ超分子结构的影响.华南理工大学学报(自然科学版). 2000, 28(3): 85~89
39李稳宏.麦秸纤维素酶解法产糖预处理过程工艺条件.西北大学学报(自然科学版), 1997, 27(3): 227~230
40谭天伟.能源生物技术.生物加工过程. 2003, 5(1): 32~36
41 Michael Kaylen. Economic feasibility of producing ethanol from lignocellulosic feedstocks. Bioresource Technology. 2000, 72(6): 19~32
42 Ye Sun, Jiayang Cheng. Hydrolysis of lignocellulosic materials for ethanolproduction:a review.Bioresource Technology. 2002, 83(4): 1~11
43 Eliasson A, Christensson C, Wahlbom CF. Anaerobic xylose fermentation by recombinant Saccharomyces cerevisiae harbouring XYL1, XYL2 and XKS1 in mineral media chemostat cultivations. Appl Environ Microbiol. 2000, 66(6): 1~6
44 Jeffries TW, Shi NQ. Genetic engineering for improved xylose fermentation by yeasts. Adv Biochem Eng Biotechnol. 1999, 65(10): 17~61
45 Eliasson A. Xylose fermentation by mutant and wild-type strains of dygosaccharomyces and Saccharomyces cerevisiae. Appl Microbiol Biotechnol. 2000, 53(3): 76~82
46 R.Ptengerdy, G.Szakacs. Bioconversion of lignocellulose in solid substrate fermentation. Biochemical Engineering Journal. 2003, 13: 169~179
47 PhilippB. Lignocellulosics-science, technology development and useeds. Ellis Horwood Limited. 1992, 467~477
48 Wyman CE. Ethanol from lignocellulosic biomass technology economics and opportunities. Bioresour Technol. 1994, 50: 3~16
49 Wu Z W, LeeW X. Nonisothermal simultaneous saccharification and fermentation for direct conversion of lighcellulosic biomass to ethanol. Appl Biochem Biotechnol. 1992, 34: 639~649
2朱圣东.微波技术用于植物纤维素原料生产酒精的研究.2005:3~60
3 Nathan Mosier. Optimization of pH controlled liquid hot water pretreatment of corn stover. Bioresource Technology. 2005,96: 1986~1993
4 Chaogang Liu, Charles E. Wyman. Partial flow of compressed-hot water through corn stover to enhance hemicellulose sugar recovery and enzymatic digestibility of cellulose.Bioresource Technology. 2005, 96: 1978~1985
5 Badal C. Saha, Loren B. Iten, Michael A. Cotta, Y. Victor Wu. Dilute acid pretreatment, enzymatic saccharification and fermentation of wheat straw to ethanol. Process Biochemistry. 2005, 40: 3693~3700
6 Tae Hyun Kim, Yoon Y. Lee. Pretreatment and fractionation of corn stover by ammonia recycle percolation process. Bioresource Technology. 2005, 96: 2007~2013
7 Sehoon Kim, Mark T. Holtzapple. Lime pretreatment and enzymatic hydrolysis of corn stover.Bioresource Technology. 2005, 96: 1994~2006
8杨伯伦,贺拥军.微波加热在化学反应中的应用进展.现代化工. 2001,21(4): 8~13
9王继业,许赤兵,宋会花等.微波加热在无机固相反应中的应用.河北师范大学学报(自然科学版). 2004,28(4):396~400
10贾艳宗,马沛生,王彦飞.微波在酯化和水解反应中的应用.化工进展. 2004,23(6):641~645
11胡同亮,李萍,张起凯等.微波辐射法原油脱水的研究.炼油技术与工程. 2003,33(2):6~8
12王金成,熊力.微波在环境化学中的应用.气象水文海洋仪器. 2001, (2):44~49
13杨强.微波技术在环境保护中的应用.环境保护. 2001,1:41~43
14李冬梅.玉米秸秆制取燃料酒精的细菌筛选及工艺研究.哈尔滨工业大学理学硕士学位论文.2005:25~50
15 Charles E. Wyman, Bruce E. Dale, Richard T. Elander. Comparative sugarrecovery data from laboratory scale application of leading pretreatment technologies to corn stover. Bioresource Technology. 2005, 96: 2026~2032
16安宏.纤维素水解制取燃料酒精的试验研究.浙江大学硕士学位论文.2005:5~32
17 Farzaneh Teymouri, Lizbeth Laureano-Perez, Hasan Alizadeh, Bruce E.Dale. Optimization of the ammonia fiber explosion (AFEX) treatment parameters for enzymatic hydrolysis of corn stover. Bioresource Technology. 2005, 96: 2014~2018
18 Tae Hyun Kim, Y.Y. Lee. Fractionation of corn stover by hot-water and aqueous ammonia treatment. Bioresource Technology. 2006, 97: 224~232
19 Badal C. Saha, Loren B. Iten, Michael A. Cotta, Y. Victor Wu. Dilute acid pretreatment, enzymatic saccharification and fermentation of wheat straw to ethanol. Biomass and Bioenergy. 2005, 28: 411~417
20 Hongzhang Chen, Liying Liu, Xuexia Yang, Zuohu Li. New process of maize stalk amination treatment by steam explosion. Biomass and Bioenergy. 2005, 28: 411~417
21 Todd A. Lloyd, Charles E. Wyman. Combined sugar yields for dilute sulfuric acid pretreatment of corn stover followed by enzymatic hydrolysis of the remaining solids. Bioresource Technology. 2005, 96: 1959~1966
22 Ye Sun, Jay J. Cheng. Dilute acid pretreatment of rye straw and bermudagrass for ethanol production. Bioresource Technology. 2005, 96: 1599~1606
23 Todd A. Lloyd, Charles E. Wyman. Combined sugar yields for dilute sulfuric acid pretreatment of corn stover followed by enzymatic hydrolysis of the remaining solids. Bioresource Technology. 2005, 96: 1967~1977
24 N. Rao Lakkakula, Marybeth Lima, Terry Walker. Rice bran stabilization and rice bran oil extraction using ohmic heating q. Bioresource Technology. 2004, 92: 157~161
25 Beatriz Palmarola-Adrados. Pretreatment of barley husk for bioethanol production. Journal of Chemical Technology and Biotechnology. 2005, 80: 85~91
26 A. Domnguez, J.A. Menendez. Production of bio-fuels by high temperature pyrolysis ofsewage sludge using conventional and microwaveheating.Bioresource Technology. 2006, 97: 1185~1193
27 B. Palmarola Adrados. Size exclusion behavior of hydroxypropylcellulose beads with temperature-dependent porosity. Journal of Chromatography A. 2001, 930: 73~78
28 Shengdong Zhu, Yuanxin Wu. The effect of microwave irradiation on enzymatic hydrolysis of rice straw. Bioresource Technology. 2006, 97: 1964~1968
29 Klaus Fischer. Generation of organic acids and monosaccharides by hydrolytic and oxidative transformation of food processing residues. Bioresource Technology. 2005, 96: 831~842
30 A. Kaminskal, M. Sawczak. The effect of wavelength and fluence on the cellulose degradation of laser-cleaned paper. Laser Physics and Applications: 382~386
31 Meijuan Zeng, Nathan S. Mosier. Microscopic Examination of Changes of Plant Cell Structure in Corn Stover Due to Hot Water Pretreatment and Enzymatic Hydrolysis: 265~277
32黄宇彤.世界燃料酒精生产形势.酿酒. 2001, 28(5): 12~15
33刘洪凤.秸秆纤维性能.东华大学学报. 2002, 2(28): 123~127
34孙健.纤维素原料生产燃料酒精的技术现状.可再生能源. 2003, 6(2): 5~9.
35卢雪梅,马登波,高培基.纤维素酶活的测定.纤维素科学与技术. 1994, 2(4): 24
36李佐虎,岑沛霖.纤维素酒精的分散、耦合、并行系统.生物技术通报. 1999, 4: 27~29
37刘家健,陆怡.预处理对纤维素酶降解影响的研究.林产化学与工业. 1995, 15(3): 67~71
38熊键.微波对纤维素Ⅰ超分子结构的影响.华南理工大学学报(自然科学版). 2000, 28(3): 85~89
39李稳宏.麦秸纤维素酶解法产糖预处理过程工艺条件.西北大学学报(自然科学版), 1997, 27(3): 227~230
40谭天伟.能源生物技术.生物加工过程. 2003, 5(1): 32~36
41 Michael Kaylen. Economic feasibility of producing ethanol from lignocellulosic feedstocks. Bioresource Technology. 2000, 72(6): 19~32
42 Ye Sun, Jiayang Cheng. Hydrolysis of lignocellulosic materials for ethanolproduction:a review.Bioresource Technology. 2002, 83(4): 1~11
43 Eliasson A, Christensson C, Wahlbom CF. Anaerobic xylose fermentation by recombinant Saccharomyces cerevisiae harbouring XYL1, XYL2 and XKS1 in mineral media chemostat cultivations. Appl Environ Microbiol. 2000, 66(6): 1~6
44 Jeffries TW, Shi NQ. Genetic engineering for improved xylose fermentation by yeasts. Adv Biochem Eng Biotechnol. 1999, 65(10): 17~61
45 Eliasson A. Xylose fermentation by mutant and wild-type strains of dygosaccharomyces and Saccharomyces cerevisiae. Appl Microbiol Biotechnol. 2000, 53(3): 76~82
46 R.Ptengerdy, G.Szakacs. Bioconversion of lignocellulose in solid substrate fermentation. Biochemical Engineering Journal. 2003, 13: 169~179
47 PhilippB. Lignocellulosics-science, technology development and useeds. Ellis Horwood Limited. 1992, 467~477
48 Wyman CE. Ethanol from lignocellulosic biomass technology economics and opportunities. Bioresour Technol. 1994, 50: 3~16
49 Wu Z W, LeeW X. Nonisothermal simultaneous saccharification and fermentation for direct conversion of lighcellulosic biomass to ethanol. Appl Biochem Biotechnol. 1992, 34: 639~649