Effect of steam explosion pretreatment on pore size and enzymatic hydrolysis of poplar

Grous, William R.; Converse, Alvin O.; Grethlein, Hans E.

doi:10.1016/0141-0229(86)90021-9

Cited by 260 publications

(133 citation statements)

References 12 publications

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“…Air-drying of biomass samples is thought to irreversibly collapse the capillary structure (Esteghlalian et al, 2001;Weise, 1998), significantly decreasing internal surface area (Stone and Scallan, 1968;Browning, 1975). Consequently, biomass sample drying is generally understood to negatively affect the enzymatic digestibility of the cellulose fraction in biomass by limiting enzyme access (Esteghlalian et al, 2001;Fan et al, 1980a;Grous et al, 1986). The effect of drying on pulp is described as ''hornification,'' where the complete removal of moisture allows adjacent cellulose fibers to form hydrogen bonds (Weise, 1998).…”

Section: Discussionmentioning

confidence: 99%

“…The opposite of ''opening up'' the structure of biomass to increase cellulase access is to collapse the structure to limit access, which is thought to occur when a biomass sample is dried (Esteghlalian et al, 2001;Grous et al, 1986). The water content in biomass affects the degree of swelling (Browning, 1975), the crystallinity (Fan et al, 1981) and the digestibility (Focher et al, 1981) of cellulose microfibrils.…”

Section: Discussionmentioning

confidence: 99%

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Cellulase digestibility of pretreated biomass is limited by cellulose accessibility

Jeoh¹,

Ishizawa²,

Davis³

et al. 2007

Biotech & Bioengineering

460

321

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Attempts to correlate the physical and chemical properties of biomass to its susceptibility to enzyme digestion are often inconclusive or contradictory depending on variables such as the type of substrate, the pretreatment conditions and measurement techniques. In this study, we present a direct method for measuring the key factors governing cellulose digestibility in a biomass sample by directly probing cellulase binding and activity using a purified cellobiohydrolase (Cel7A) from Trichoderma reesei. Fluorescence-labeled T. reesei Cel7A was used to assay pretreated corn stover samples and pure cellulosic substrates to identify barriers to accessibility by this important component of cellulase preparations. The results showed cellulose conversion improved when T. reesei Cel7A bound in higher concentrations, indicating that the enzyme had greater access to the substrate. Factors such as the pretreatment severity, drying after pretreatment, and cellulose crystallinity were found to directly impact enzyme accessibility. This study provides direct evidence to support the notion that the best pretreatment schemes for rendering biomass more digestible to cellobiohydrolase enzymes are those that improve access to the cellulose in biomass cell walls, as well as those able to reduce the crystallinity of cell wall cellulose.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Cellulase digestibility of pretreated biomass is limited by cellulose accessibility

Jeoh¹,

Ishizawa²,

Davis³

et al. 2007

Biotech & Bioengineering

460

321

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“…Examples include physical (e.g., limited pyrolysis and mechanical disruption/comminution, Mosier et al, 2005), physicochemical (e.g., steam explosion, ammonia fiber explosion, Grous et al, 1986;Mes-Hartree et al, 1988), chemical (e.g., acid hydrolysis, alkaline hydrolysis, high temperature organic solvent pretreatment, oxidative delignification, Chum et al, 1988;Gierer and Noren, 1982;Zhang et al, 2007), and biological (e.g., lignin degradation by white-and soft-rot fungi, Hatakka, 1983;Lee, 1997) methods. In all cases, upon sufficient removal of the lignin, there was also substantial degradation of lignin and in many cases there was substantial loss in fermentable sugar content of the residual polysaccharides (Galbe and Zacchi, 2007).…”

Section: Introductionmentioning

confidence: 99%

Ionic liquid‐mediated selective extraction of lignin from wood leading to enhanced enzymatic cellulose hydrolysis

Lee

Doherty

Linhardt

et al. 2008

Biotech & Bioengineering

848

571

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Lignocellulose represents a key sustainable source of biomass for transformation into biofuels and bio-based products. Unfortunately, lignocellulosic biomass is highly recalcitrant to biotransformation, both microbial and enzymatic, which limits its use and prevents economically viable conversion into value-added products. As a result, effective pretreatment strategies are necessary, which invariably involves high energy processing or results in the degradation of key components of lignocellulose. In this work, the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([Emim][CH 3 COO]), was used as a pretreatment solvent to extract lignin from wood flour. The cellulose in the pretreated wood flour becomes far less crystalline without undergoing solubilization. When 40% of the lignin was removed, the cellulose crystallinity index dropped below 45, resulting in >90% of the cellulose in wood flour to be hydrolyzed by Trichoderma viride cellulase. [Emim] [CH 3 COO] was easily reused, thereby resulting in a highly concentrated solution of chemically unmodified lignin, which may serve as a valuable source of a polyaromatic material as a value-added product.

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“…These pretreatments include dilute acid (Lloyd and Wyman 2005;Saha et al 2005;Schell et al 2003), hot water (Liu and Wyman 2004;Ruiz et al 2013), ammonia fiber expansion (Hoover et al 2014;Lau et al 2008;Murnen et al 2007), steam explosion (Grous et al 1986;Kaar et al 1998), lime (Chang et al 1997;Kim and Holtzapple 2005), organic solvent (Zhang et al 2007;Zhao et al 2009b), and pyrolysis and mechanical disruption (Mosier et al 2005). In all these treatments, the substantial degradation of lignin is accompanied by considerable reduction in fermentable sugar content of the feedstock, resulting in a loss of 20-35% of the mass of lignocellulose (Galbe and Zacchi 2007;Lee et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Ionic liquid-tolerant microorganisms and microbial communities for lignocellulose conversion to bioproducts

Simmons

Singer

et al. 2016

Appl Microbiol Biotechnol

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Chemical and physical pretreatment of biomass is a critical step in the conversion of lignocellulose to biofuels and bioproducts. Ionic liquid (IL) pretreatment has attracted significant attention due to the unique ability of certain ILs to solubilize some or all components of the plant cell wall. However, these ILs not only inhibit enzyme activities, but also the growth and productivity of microorganisms used in downstream hydrolysis and fermentation processes.While pretreated biomass can be washed to remove residual IL and reduce inhibition, extensive washing is costly and not feasible in large-scale processes. IL tolerant microorganisms and microbial communities have been discovered from environmental samples and studies begun to elucidate mechanisms of IL tolerance. The discovery of IL tolerance in environmental microbial communities and individual microbes has lead to the proposal of molecular mechanisms of resistance. In this article, we review recent progress on discovering IL tolerant microorganisms, identifying metabolic pathways and mechanisms of tolerance, and engineering microorganisms for IL tolerance. Research in these areas will yield new approaches to overcome inhibition in lignocellulosic biomass bioconversion processes and increase opportunities for the use of ILs in biomass pretreatment.

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Effect of steam explosion pretreatment on pore size and enzymatic hydrolysis of poplar

Cited by 260 publications

References 12 publications

Cellulase digestibility of pretreated biomass is limited by cellulose accessibility

Cellulase digestibility of pretreated biomass is limited by cellulose accessibility

Ionic liquid‐mediated selective extraction of lignin from wood leading to enhanced enzymatic cellulose hydrolysis

Ionic liquid-tolerant microorganisms and microbial communities for lignocellulose conversion to bioproducts

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