Mechanism of lignocellulose modification and enzyme disadsorption for complete biomass saccharification to maximize bioethanol yield in rapeseed stalks

Jun, Deng; Zhu, Xiaobo; Chen, Peng; He, Boyang; Tang, Shang-wen; Zhao, Wenyue; Li, Xianliang; Zhang, Ran; Lv, Zhengyi; Kang, Heng; Yu, Li; Peng, Liangcai

doi:10.1039/c9se00906j

Cited by 38 publications

(18 citation statements)

References 49 publications

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“…Cellulose structure, especially crystallinity, has been also linked to saccharification but results have been conflicting [ 17 , 18 ] or reported little or no effect [ 19 , 20 ]. At the scale of polymers, the degree of polymerization of the cellulose [ 14 , 21 – 23 ], presence of acetyl groups [ 24 ] as well as the occurrence of sugar substituents can also limit enzymatic hydrolysis by preventing enzymes from accessing glycosidic linkages reviewed by [ 25 ]. Many pretreatments before the saccharification step aim to reduce the detrimental impact of these components [ 12 , 14 , 26 – 32 ].…”

Section: Introductionmentioning

confidence: 99%

Enzymatic degradation of maize shoots: monitoring of chemical and physical changes reveals different saccharification behaviors

Barron

Devaux

Foucat

et al. 2021

Biotechnol Biofuels

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Background The recalcitrance of lignocellulosics to enzymatic saccharification has been related to many factors, including the tissue and molecular heterogeneity of the plant particles. The role of tissue heterogeneity generally assessed from plant sections is not easy to study on a large scale. In the present work, dry fractionation of ground maize shoot was performed to obtain particle fractions enriched in a specific tissue. The degradation profiles of the fractions were compared considering physical changes in addition to chemical conversion. Results Coarse, medium and fine fractions were produced using a dry process followed by an electrostatic separation. The physical and chemical characteristics of the fractions varied, suggesting enrichment in tissue from leaves, pith or rind. The fractions were subjected to enzymatic hydrolysis in a torus reactor designed for real-time monitoring of the number and size of the particles. Saccharification efficiency was monitored by analyzing the sugar release at different times. The lowest and highest saccharification yields were measured in the coarse and fine fractions, respectively, and these yields paralleled the reduction in the size and number of particles. The behavior of the positively- and negatively-charged particles of medium-size fractions was contrasted. Although the amount of sugar release was similar, the changes in particle size and number differed during enzymatic degradation. The reduction in the number of particles proceeded faster than that of particle size, suggesting that degradable particles were degraded to the point of disappearance with no significant erosion or fragmentation. Considering all fractions, the saccharification yield was positively correlated with the amount of water associated with [5–15 nm] pore size range at 67% moisture content while the reduction in the number of particles was inversely correlated with the amount of lignin. Conclusion Real-time monitoring of sugar release and changes in the number and size of the particles clearly evidenced different degradation patterns for fractions of maize shoot that could be related to tissue heterogeneity in the plant. The biorefinery process could benefit from the addition of a sorting stage to optimise the flow of biomass materials and take better advantage of the heterogeneity of the biomass.

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Section: Introductionmentioning

confidence: 99%

Enzymatic degradation of maize shoots: monitoring of chemical and physical changes reveals different saccharification behaviors

Barron

Devaux

Foucat

et al. 2021

Biotechnol Biofuels

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“…As a major contributor to the recalcitrance, lignin forms a physical barrier against cellulase accession by interlinking with hemicellulose and cellulose (Haarmeyer et al., 2017; Li et al., 2014; Zeng et al., 2014). Recently, lignin has been examined to adsorb cellulases, which affects enzymatic hydrolysis of lignocellulose (Deng et al., 2020; Jin et al., 2016). Harsh physical and chemical pretreatments are thus required for effective lignin extraction, demanding high energy input and leading to potential secondary chemical pollution in the environment (Himmel et al., 2007).…”

Section: Introductionmentioning

confidence: 99%

Distinctively altered lignin biosynthesis by site‐modification of OsCAD2 for enhanced biomass saccharification in rice

Zhang

Wang

et al. 2020

GCB Bioenergy

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Crop straws represent enormous biomass resource convertible for biofuels and bioproducts, but lignocellulose recalcitrance restricts its saccharification for commercial utility. Despite genetic modification of lignin biosynthesis being attempted to reduce recalcitrance in bioenergy crops, it remains challenging to optimize lignin deposition without an unacceptable yield penalty. Based on gene expression analysis and phylogenetic tree profiling, a cinnamyl alcohol dehydrogenase gene (OsCAD2) as the target for genetic engineering of lignin biosynthesis in rice was selected in this study. Using CRISPR/Cas9 technology, independent homozygous transgenic lines with precise site mutation of OsCAD2, which showed slightly reduced lignin levels but markedly decreased p‐hydroxyphenyl (H) contents in lignin by 34% and increased guaiacyl (G) contents by 16%, compared to the wild type were generated in this study. Under mild alkali pretreatment (1% NaOH, 50°C), the OsCAD2 site‐modified lines showed effective lignin extraction up to 70% (of total lignin) from mature rice straws, which caused either significantly increased biomass porosity and cellulose accessibility or remarkably reduced cellulase adsorption to lignin in pretreated lignocellulose residues. These consequently led to almost complete biomass enzymatic saccharification with increased hexoses yields by 61%–72% in the modified lines, being much higher than those of the lignin‐altered lines reported in previous studies. Hence, this study has demonstrated a novel genetic engineering strategy to reduce lignocellulose recalcitrance with minimized biomass loss for cost‐effective biomass conversion to bioethanol in rice and bioenergy crops.

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“…Biomass enzymatic saccharification refers to hexoses yield against cellulose (% cellulose) released from enzymatic hydrolysis of the pretreated biomass residues (Li et al., 2013; Wu et al., 2013; Xu et al., 2012). Using our previously established approaches (Deng et al., 2020; Huang et al., 2012), this study performed acid (H 2 SO 4 ) and alkali (NaOH, CaO) pretreatments at series of concentrations and determined the hexoses yields released from enzymatic hydrolysis while co‐supplied with 1% Tween‐80 (Figure 2). As a result, the P. simonii sample showed consistently higher hexoses yields than those of other six biomass samples under all chemical pretreatments performed in this study.…”

Section: Resultsmentioning

confidence: 99%

“…Chemical pretreatment and sequential enzymatic hydrolysis were performed as previously described (Deng et al., 2020; Huang et al., 2012). Biomass samples (0.3 g) were, respectively, incubated with H 2 SO 4 or NaOH at five concentrations (0.5%, 1%, 2%, 4%, 8%, v/v for H 2 SO 4 , w/v for NaOH, respectively), or with CaO at five concentrations (1%, 2.5%, 5%, 10%, 20%, w/w).…”

Section: Methodsmentioning

confidence: 99%

“…However, both pretreatments under strong conditions not only produce toxic compounds that inhibit yeast fermentation but also release the secondary wastes into the environment (Franden et al, 2013;Li, Si, et al, 2014;Si et al, 2015). Due to its recycling and adsorption with toxic compounds, CaO chemical has been applied for a green-like pretreatment performed under mild condition, but the CaO pretreatment is only effective for the desirable bioenergy plants that are of relatively weak lignocellulose recalcitrance (Deng et al, 2020;van der Pol et al, 2014). In this study, we collected totally seven biomass samples from three major hardwood species (poplar, salix and eucalyptus) that are widely distributed over the world, and compared their distinct biomass enzymatic saccharification under acid (H 2 SO 4 ) and alkali (NaOH, CaO) pretreatments at a series of concentrations.…”

Section: Introductionmentioning

confidence: 99%

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Ecologically adaptable Populus simonii is specific for recalcitrance‐reduced lignocellulose and largely enhanced enzymatic saccharification among woody plants

Liu

Zhang

et al. 2020

GCB Bioenergy

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Woody plants provide enormous biomass resource convertible for biofuels and bioproducts, but they are of typical lignified secondary cell walls with strong recalcitrance against biomass degradation. It thus becomes critical to find out the desirable woody plant enabled for efficient biomass enzymatic saccharification. In this study, we collected totally seven biomass samples from three major hardwood species showing worldwide geographic distributions and diverse cell wall compositions. Under acid (H2SO4) and alkali (NaOH, CaO) pretreatments, all biomass samples showed remarkably enhanced enzymatic saccharification, but the Populus simonii species had the highest hexoses yields from all pretreatments performed. In particular, the mild and green‐like pretreatment (10% CaO, 50°C) could lead to more than 70% cellulose degradation into fermentable hexoses in the P. simonii species, but only 24%–38% cellulose digestions were examined in the other six samples. Importantly, the P. simonii species is of the lowest ratios of lignin S/G and hemicellulose Xyl/Ara among seven samples, being two major factors accountable for much improved lignocellulose recalcitrance. These consequently caused the most reduced cellulose DP in the pretreated P. simonii residues for enhanced biomass saccharification. Furthermore, this study performed a genome‐wide profiling of gene expression to confirm distinct wall polymer biosynthesis and biomass metabolism in the P. simonii species, consistent with its significantly improved lignocellulose recalcitrance. Therefore, this study has found out the desirable model of woody plants for efficient biomass enzymatic saccharification under cost‐effective and green‐like pretreatments, providing a powerful strategy for genetic lignocellulose modification in woody plants and beyond.

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Mechanism of lignocellulose modification and enzyme disadsorption for complete biomass saccharification to maximize bioethanol yield in rapeseed stalks

Abstract: An integrated strategy for complete lignocellulose saccharification to maximize bioethanol yield under a cost-effective and green-like biomass process in rapeseed stalk.

Cited by 38 publications

References 49 publications

Enzymatic degradation of maize shoots: monitoring of chemical and physical changes reveals different saccharification behaviors

Enzymatic degradation of maize shoots: monitoring of chemical and physical changes reveals different saccharification behaviors

Distinctively altered lignin biosynthesis by site‐modification of OsCAD2 for enhanced biomass saccharification in rice

Ecologically adaptable Populus simonii is specific for recalcitrance‐reduced lignocellulose and largely enhanced enzymatic saccharification among woody plants

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