Progress in Ultrasound Intensification for Enzymatic Hydrolysis of Lignocellulose

doi:10.13560/j.cnki.biotech.bull.1985.2021-0116

Abstract

Abstract:

Ultrasonic treatment can intensify enzymatic hydrolysis process of lignocellulosic biomass,which is beneficial to improving the enzymatic hydrolysis rate and the production of fermentable sugar and bioethanol. This paper reviews enzymatic hydrolysis process of lignocellulose and factors limiting enzymatic hydrolysis,as well as the applications of ultrasound on pretreatment of enzyme-substrate systems,saccharification,simultaneous saccharification and fermentation,and cellulase production. Ultrasonic treatment enhances the bioconversion of lignocellulosic in many ways and provides obvious reinforcement effect on enzymatic reactions. The mechanisms of ultrasonic intensification on enzymatic hydrolysis were analyzed. Ultrasonic treatment improves the process of mass transfer and diffusion of heterogeneous system,increases the enzyme/substrate affinity,enhances the conversion of enzyme/substrate complex into product,changes the conformation of enzyme molecules flexibly to locate on the substrate easily,breaks enzymatic molecular aggregates,and makes the enzyme active sites easier to react. Moreover,it increases the accessibility of cellulose substrates. Ultrasonic waves alters the spatial structure of the enzyme protein,causing favorable conformation changes to the enzyme without destroying its structural integrity,so that the active sites of the enzyme can be more fully exposed and the enzyme activity can be improved. The paper discusses whether or not cellulase activity decreases by ultrasonic treatment,the important influence of ultrasonic reactor type and parameter setting on the research results,and the economic benefit evaluation of ultrasonic intensified enzymatic hydrolysis of lignocellulose. Finally the paper puts forward the further research direction in the aspects of the synergistic effect of ultrasonic enhancement and other enzymatic improvement measures,the in-depth study of mechanism and the comprehensive optimization of operation parameters.

Key words: lignocellulose, enzymatic hydrolysis, cellulase, ultrasound

HU Fang, DONG Xu, SHI Chang-wei, WU Xue-dong. Progress in Ultrasound Intensification for Enzymatic Hydrolysis of Lignocellulose[J]. Biotechnology Bulletin, 2021, 37(10): 234-244.

Figures/Tables 2

References 50

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强化途径 Intensification approch	原料 Materials	超声波参数 Ultrasonic parameters	主要影响 Main effects	文献Reference
超声波预处理酶-底物 Ultrasound pretreatment of enzyme-substrate	甘蔗渣 Sugarcane bagasse	150.7 W/cm²、20 kHz	还原糖浓度达到对照样的1.9倍 Concentration of reducing sugar was 1.9 times of the control	[1]
超声波强化糖化 Ultrasound intensification of saccharification	旧报纸Old newspaper	60 W、20 kHz、占空比70% 60 W、20 kHz、70% duty cycle	还原糖浓度达到对照样的2.4倍 Concentration of reducing sugar was 2.4 times of the control	[17]
	花生壳、椰子壳和开心果壳 Groundnut shells, coconut coir and pistachio shells	80 W、20 kHz、占空比70% 80 W、20kHz、70% duty cycle	还原糖产量达到对照样的2倍 Concentration of reducing sugar was double of the control	[18]
	玉米芯Corncob	280 W和500 W、20 kHz、占空比50%、 280 W and 500 W、20 kHz、50% duty cycle	葡聚糖消化率分别提高75.6%和58.9% Glucan digestibilities were increased 75.6% and 58.9%, respectively	[19]
	稻草Rice straw	300 W、40 kHz	总还原糖产率增加19.5% Yield of total reducing sugar with ultrasound increased by 19.5%	[20]
	银胶菊Parthenium hysterophorus	35 W、35 kHz、占空比10% 35 W、35 kHz、10% duty cycle	酶解动力学提高6倍,总还原糖产量增加约20% Kinetics of hydrolysis showed a marked 6× increase with sonication, while total reducing sugar yield showed rise of 20%	[21]
	银胶菊Parthenium hysterophorus	35 W、35 kHz、占空比50% 35 W、35 kHz、50% duty cycle	酶解动力学提高18倍,酶解时间从72 h减少到仅4 h 18-fold increase in the kinetics of enzymatic hydrolysis was seen with ultrasound, and the hydrolysis time reduced from 72 h to just 4 h	[22]
	甜根子草、薇甘菊、马缨丹和凤眼莲 Saccharum spontaneum, Mikania micrantha, Lantana camara and Eichhornia crassipes）	35 W、35 kHz、占空比为10% 35 W、35 kHz、10% duty cycle	酶解动力学提高近10倍 Kinetics of enzymatic hydrolysis increased by 10-fold	[23]
	玉米秸秆Corn stover	80 W、20 kHz	催化效率提高约70% Catalytic efficiency of cellulase increased by 70%	[24]
	甘蔗渣Sugarcane bagasse	132 W、40 kHz	提高葡萄糖产量 Yield of glucose increased	[25]
	甘蔗渣Sugarcane bagasse	240 W、24 kHz,30 min/30 s超声波处理 240 W、24 kHz, 30 s ultrasound irradiation for every 30 min of incubation	提高葡萄糖和乙醇产量 Improved the sugars and ethanol yield	[26]
	甘蔗渣Sugarcane bagasse	60 W/cm²、24 kHz	在直接和间接超声作用下,水解产物的最高产率分别为31.3 g/kg和60.6 g/kg Maximum yield of hydrolysis were 31.3 g/kg and 60.6 g/kg respectively under direct and indirect sonication, respectively	[27]
	木屑Sawdust	50 W、20 kHz、占空比70% 50 W、20 kHz、70% duty cycle	1 h 超声波强化酶解,与常规搅拌 3h的还原糖产率相当 Ultrasound intensified enzymatic hydrolysis within 1 h resulted in approximately same yield of reducing sugars within 3 h with conventional stirring	[28]
超声波强化SSF Ultrasound intensification of SSF	甘蔗渣Sugarcane bagasse	240 W、24 KH、每30 min进行30 s超声波处理 240 W、24 kHz, 30 s ultrasound irradiation for every 30 min of incubation	提高发酵速率 Increased the rate of fermentation was higher	[26]
	银胶菊 Parthenium hysterophorus	35 W、35 kHz、占空比为10% 35 W、35 kHz、10% duty cycle	加速发酵和酶解 Fermentation and enzymatic hydrolysis were enhanced	[29]
	棕榈叶Oil palm fronds	200 W、37 kHz	最大乙醇浓度18.2 g/L,产率57% Maximal bioethanol concentration was 18.2 g/L and yield was 57.0%	[30]
超声波强化产酶 Ultrasound intensification of cellulase production	甘蔗渣Sugarcane bagasse	240 W、24 kHz,每6 h进行30 s超声波处理 240 W、24 kHz,30 s ultrasound irradiation for every 6 h of incubation	增加分生孢子数量;蛋白质浓度提高1.4倍 Produced conidia showed higher intensity, the protein concentration increased 1.4 fold	[26]

强化途径 Intensification approch	原料 Materials	超声波参数 Ultrasonic parameters	主要影响 Main effects	文献Reference
超声波预处理酶-底物 Ultrasound pretreatment of enzyme-substrate	甘蔗渣 Sugarcane bagasse	150.7 W/cm²、20 kHz	还原糖浓度达到对照样的1.9倍 Concentration of reducing sugar was 1.9 times of the control	[1]
超声波强化糖化 Ultrasound intensification of saccharification	旧报纸Old newspaper	60 W、20 kHz、占空比70% 60 W、20 kHz、70% duty cycle	还原糖浓度达到对照样的2.4倍 Concentration of reducing sugar was 2.4 times of the control	[17]
	花生壳、椰子壳和开心果壳 Groundnut shells, coconut coir and pistachio shells	80 W、20 kHz、占空比70% 80 W、20kHz、70% duty cycle	还原糖产量达到对照样的2倍 Concentration of reducing sugar was double of the control	[18]
	玉米芯Corncob	280 W和500 W、20 kHz、占空比50%、 280 W and 500 W、20 kHz、50% duty cycle	葡聚糖消化率分别提高75.6%和58.9% Glucan digestibilities were increased 75.6% and 58.9%, respectively	[19]
	稻草Rice straw	300 W、40 kHz	总还原糖产率增加19.5% Yield of total reducing sugar with ultrasound increased by 19.5%	[20]
	银胶菊Parthenium hysterophorus	35 W、35 kHz、占空比10% 35 W、35 kHz、10% duty cycle	酶解动力学提高6倍,总还原糖产量增加约20% Kinetics of hydrolysis showed a marked 6× increase with sonication, while total reducing sugar yield showed rise of 20%	[21]
	银胶菊Parthenium hysterophorus	35 W、35 kHz、占空比50% 35 W、35 kHz、50% duty cycle	酶解动力学提高18倍,酶解时间从72 h减少到仅4 h 18-fold increase in the kinetics of enzymatic hydrolysis was seen with ultrasound, and the hydrolysis time reduced from 72 h to just 4 h	[22]
	甜根子草、薇甘菊、马缨丹和凤眼莲 Saccharum spontaneum, Mikania micrantha, Lantana camara and Eichhornia crassipes）	35 W、35 kHz、占空比为10% 35 W、35 kHz、10% duty cycle	酶解动力学提高近10倍 Kinetics of enzymatic hydrolysis increased by 10-fold	[23]
	玉米秸秆Corn stover	80 W、20 kHz	催化效率提高约70% Catalytic efficiency of cellulase increased by 70%	[24]
	甘蔗渣Sugarcane bagasse	132 W、40 kHz	提高葡萄糖产量 Yield of glucose increased	[25]
	甘蔗渣Sugarcane bagasse	240 W、24 kHz,30 min/30 s超声波处理 240 W、24 kHz, 30 s ultrasound irradiation for every 30 min of incubation	提高葡萄糖和乙醇产量 Improved the sugars and ethanol yield	[26]
	甘蔗渣Sugarcane bagasse	60 W/cm²、24 kHz	在直接和间接超声作用下,水解产物的最高产率分别为31.3 g/kg和60.6 g/kg Maximum yield of hydrolysis were 31.3 g/kg and 60.6 g/kg respectively under direct and indirect sonication, respectively	[27]
	木屑Sawdust	50 W、20 kHz、占空比70% 50 W、20 kHz、70% duty cycle	1 h 超声波强化酶解,与常规搅拌 3h的还原糖产率相当 Ultrasound intensified enzymatic hydrolysis within 1 h resulted in approximately same yield of reducing sugars within 3 h with conventional stirring	[28]
超声波强化SSF Ultrasound intensification of SSF	甘蔗渣Sugarcane bagasse	240 W、24 KH、每30 min进行30 s超声波处理 240 W、24 kHz, 30 s ultrasound irradiation for every 30 min of incubation	提高发酵速率 Increased the rate of fermentation was higher	[26]
	银胶菊 Parthenium hysterophorus	35 W、35 kHz、占空比为10% 35 W、35 kHz、10% duty cycle	加速发酵和酶解 Fermentation and enzymatic hydrolysis were enhanced	[29]
	棕榈叶Oil palm fronds	200 W、37 kHz	最大乙醇浓度18.2 g/L,产率57% Maximal bioethanol concentration was 18.2 g/L and yield was 57.0%	[30]
超声波强化产酶 Ultrasound intensification of cellulase production	甘蔗渣Sugarcane bagasse	240 W、24 kHz,每6 h进行30 s超声波处理 240 W、24 kHz,30 s ultrasound irradiation for every 6 h of incubation	增加分生孢子数量;蛋白质浓度提高1.4倍 Produced conidia showed higher intensity, the protein concentration increased 1.4 fold	[26]