Cellulase Adsorption and an Evaluation of Enzyme Recycle During Hydrolysis of Steam-Exploded Softwood Residues

Lu, Ye; Yang, Bin; Gregg, David J.; Saddler, John N.; Mansfield, Shawn D.

doi:10.1007/978-1-4612-0119-9_52

Cited by 36 publications

(55 citation statements)

References 20 publications

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“…Furthermore, several of these studies have only tested hydrolysis at two or three solids concentrations, thereby limiting the ability to draw conclusions on the exact relationship between solids concentration and conversion. Gradually increasing the solids concentration in the interval between 2% and 10% DM have for several substrates been demonstrated to result in a concurrent decrease in conversion in the order of 10%-20% going from 2% to 10% DM (Ingesson et al, 2001;Lu et al, 2002). However, in another study increasing the solids concentration from 2% to 5% DM resulted in a 16% decrease in cellulose conversion but a further increase to 7.5% and 10% DM resulted only in an small decrease in conversion (Tengborg et al, 2001).…”

Section: Effect Of Initial Dry Matter Content On Liquefaction and Sacmentioning

confidence: 94%

Liquefaction of lignocellulose at high‐solids concentrations

Jørgensen

Vibe-Pedersen²,

Larsen³

et al. 2006

Biotech & Bioengineering

448

322

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To improve process economics of the lignocellulose to ethanol process a reactor system for enzymatic liquefaction and saccharification at high-solids concentrations was developed. The technology is based on free fall mixing employing a horizontally placed drum with a horizontal rotating shaft mounted with paddlers for mixing. Enzymatic liquefaction and saccharification of pretreated wheat straw was tested with up to 40% (w/w) initial DM. In less than 10 h, the structure of the material was changed from intact straw particles (length 1-5 cm) into a paste/ liquid that could be pumped. Tests revealed no significant effect of mixing speed in the range 3.3-11.5 rpm on the glucose conversion after 24 h and ethanol yield after subsequent fermentation for 48 h. Low-power inputs for mixing are therefore possible. Liquefaction and saccharification for 96 h using an enzyme loading of 7 FPU/gÁDM and 40% DM resulted in a glucose concentration of 86 g/kg. Experiments conducted at 2%-40% (w/w) initial DM revealed that cellulose and hemicellulose conversion decreased almost linearly with increasing DM. Performing the experiments as simultaneous saccharification and fermentation also revealed a decrease in ethanol yield at increasing initial DM. Saccharomyces cerevisiae was capable of fermenting hydrolysates up to 40% DM. The highest ethanol concentration, 48 g/kg, was obtained using 35% (w/w) DM. Liquefaction of biomass with this reactor system unlocks the possibility of 10% (w/w) ethanol in the fermentation broth in future lignocellulose to ethanol plants.

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Section: Effect Of Initial Dry Matter Content On Liquefaction and Sacmentioning

confidence: 94%

Liquefaction of lignocellulose at high‐solids concentrations

Jørgensen

Vibe-Pedersen²,

Larsen³

et al. 2006

Biotech & Bioengineering

448

322

View full text Add to dashboard Cite

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“…The total substrate accessibility has been measured previously by using cellulase-size molecule exclusion (Burns et al, 1989;Esteghlalian et al, 2001;Grethlein, 1985;Thompson et al, 1992), low-temperature cellulase adsorption (Gerber et al, 1997;Kumar and Wyman, 2008;Lee et al, 1994;Lu et al, 2002;Mooney et al, 1998) or labeled cellulase (Jeoh et al, 2007;Palonen et al, 2004). However, in pretreated lignocellulose materials it remains relatively challenging to quantitatively differentiate accessibilities for cellulose and non-cellulose fractions.…”

Section: Introductionmentioning

confidence: 99%

Comparative study of corn stover pretreated by dilute acid and cellulose solvent‐based lignocellulose fractionation: Enzymatic hydrolysis, supramolecular structure, and substrate accessibility

Zhu

Sathitsuksanoh

Vinzant

et al. 2009

Biotech & Bioengineering

197

164

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Liberation of fermentable sugars from recalcitrant biomass is among the most costly steps for emerging cellulosic ethanol production. Here we compared two pretreatment methods (dilute acid, DA, and cellulose solvent and organic solvent lignocellulose fractionation, COSLIF) for corn stover. At a high cellulase loading [15 filter paper units (FPUs) or 12.3 mg cellulase per gram of glucan], glucan digestibilities of the corn stover pretreated by DA and COSLIF were 84% at hour 72 and 97% at hour 24, respectively. At a low cellulase loading (5 FPUs per gram of glucan), digestibility remained as high as 93% at hour 24 for the COSLIF-pretreated corn stover but reached only $60% for the DA-pretreated biomass. Quantitative determinations of total substrate accessibility to cellulase (TSAC), cellulose accessibility to cellulase (CAC), and non-cellulose accessibility to cellulase (NCAC) based on adsorption of a nonhydrolytic recombinant protein TGC were measured for the first time. The COSLIF-pretreated corn stover had a CAC of 11.57 m 2 /g, nearly twice that of the DA-pretreated biomass (5.89 m 2 /g). These results, along with scanning electron microscopy images showing dramatic structural differences between the DA-and COSLIF-pretreated samples, suggest that COSLIF treatment disrupts microfibrillar structures within biomass while DA treatment mainly removes hemicellulose. Under the tested conditions COSLIF treatment breaks down lignocellulose structure more extensively than DA treatment, producing a more enzymatically reactive material with a higher CAC accompanied by faster hydrolysis rates and higher enzymatic digestibility.

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“…Lignin can be incorporated into various polymer materials, such as silicate clays and can be used for the production of chemicals and high energy-content fuels. Lignin is considered an obstacle to realizing effective enzymatic hydrolysis and its removal is one of the goals of a successful pretreatment process [12,13]. A two-step pretreatment method was proposed to partially separate lignin from biomass, providing improved accessibility of biomass to enzymes to increase sugar yield.…”

mentioning

confidence: 99%

Ethanol production from corn stover pretreated by electrolyzed water and a two-step pretreatment method

Wang

Feng

2012

Chin. Sci. Bull.

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Pretreatment is one of the most important unit operations for ethanol production from biomass feedstocks. In this study, corn stover was used as a feedstock to examine the effectiveness of two pretreatments: electrolyzed water pretreatment and a two-step pretreatment. Electrolyzed water was employed as a catalyst to conduct one-step pretreatment of corn stover at three temperatures (165, 180 and 195°C) and three treatment times (10, 20 and 30 min). During the two-step pretreatment process, an organic alkaline solution of 1% (w/w) NaOH in 70% (w/w) ethanol was used for lignin removal in the first step, followed by a second step using hot water. No furfural or 5-hydroxymethyl furfural was detected in the hydrolysates from both pretreatment methods when the detection limit of the HPLC was 0.2 g/L. The highest glucan conversion yields were 83% obtained at 195°C for 30 min with acidic electrolyzed water and 83% by the two-step process, where the second step of the pretreatment was at 135°C for 30 min. The hydrolyzates from the two pretreatment methods showed good performance in Saccharomyces cerevisiae fermentation tests. The two new methods may provide promising alternatives for the pretreatment of biomass for ethanol production. ethanol, biomass, pretreatment, inhibitor Citation:Wang X J, Feng H, Li Z Y. Ethanol production from corn stover pretreated by electrolyzed water and a two-step pretreatment method.

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Cellulase Adsorption and an Evaluation of Enzyme Recycle During Hydrolysis of Steam-Exploded Softwood Residues

Cited by 36 publications

References 20 publications

Liquefaction of lignocellulose at high‐solids concentrations

Liquefaction of lignocellulose at high‐solids concentrations

Comparative study of corn stover pretreated by dilute acid and cellulose solvent‐based lignocellulose fractionation: Enzymatic hydrolysis, supramolecular structure, and substrate accessibility

Ethanol production from corn stover pretreated by electrolyzed water and a two-step pretreatment method

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