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Nieves, Rafael A.; Ehrman, Christine I.; Adney, William S.; Elander, Richard T.; Himmel, Michael E.

doi:10.1023/a:1008871205580

Cited by 131 publications

(27 citation statements)

References 6 publications

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“…The strains that produce cellulases used in the present study, T. reesei, have been reported to be inefficient β-glucosidase (cellobiase) secretors [51]. Hence, supplementation of Celluclast 1.5 L (cellulase), with cellobiase can decrease the concentration of cellobiose in the hydrolyzate, therefore, preventing the possible end product inhibition [52]. Spezyme® CP on the other hand contains a commercially optimized combination of endoglucanase, exoglucanase, and β-glucosidase activities [49,52,53] as indicated by the higher β-glucosidase/cellulase activity in Spezyme® CP than in Celluclast 1.5 L [52].…”

Section: Effect Of Alkali Pretreatmentmentioning

confidence: 96%

“…Hence, supplementation of Celluclast 1.5 L (cellulase), with cellobiase can decrease the concentration of cellobiose in the hydrolyzate, therefore, preventing the possible end product inhibition [52]. Spezyme® CP on the other hand contains a commercially optimized combination of endoglucanase, exoglucanase, and β-glucosidase activities [49,52,53] as indicated by the higher β-glucosidase/cellulase activity in Spezyme® CP than in Celluclast 1.5 L [52]. Agricultural residues contain comparatively higher hemicellulose (mainly xylan) than woody biomass [34], and the addition of xylanase during hydrolysis may increase monomeric sugar yields [16].…”

Section: Effect Of Alkali Pretreatmentmentioning

confidence: 99%

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Potential of Agricultural Residues and Hay for Bioethanol Production

Chen

Sharma-Shivappa

Keshwani

et al. 2007

Appl Biochem Biotechnol

157

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Production of bioethanol from agricultural residues and hays (wheat, barley, and triticale straws, and barley, triticale, pearl millet, and sweet sorghum hays) through a series of chemical pretreatment, enzymatic hydrolysis, and fermentation processes was investigated in this study. Composition analysis suggested that the agricultural straws and hays studied contained approximately 28.62-38.58% glucan, 11.19-20.78% xylan, and 22.01-27.57% lignin, making them good candidates for bioethanol production. Chemical pretreatment with sulfuric acid or sodium hydroxide at concentrations of 0.5, 1.0, and 2.0% indicated that concentration and treatment agent play a significant role during pretreatment. After 2.0% sulfuric acid pretreatment at 121°C/15 psi for 60 min, 78.10-81.27% of the xylan in untreated feedstocks was solubilized, while 75.09-84.52% of the lignin was reduced after 2.0% sodium hydroxide pretreatment under similar conditions. Enzymatic hydrolysis of chemically pretreated (2.0% NaOH or H 2 SO 4 ) solids with Celluclast 1.5 LNovozym 188 (cellobiase) enzyme combination resulted in equal or higher glucan and xylan conversion than with Spezyme® CP-xylanase combination. The glucan and xylan conversions during hydrolysis with Celluclast 1.5 L-cellobiase at 40 FPU/g glucan were 78.09 to 100.36% and 74.03 to 84.89%, respectively. Increasing the enzyme loading from 40 to 60 FPU/g glucan did not significantly increase sugar yield. The ethanol yield after fermentation of the hydrolyzate from different feedstocks with Saccharomyces cerevisiae ranged from 0.27 to 0.34 g/g glucose or 52.00-65.82% of the theoretical maximum ethanol yield.

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Section: Effect Of Alkali Pretreatmentmentioning

confidence: 96%

Section: Effect Of Alkali Pretreatmentmentioning

confidence: 99%

Potential of Agricultural Residues and Hay for Bioethanol Production

Chen

Sharma-Shivappa

Keshwani

et al. 2007

Appl Biochem Biotechnol

157

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“…In order to study the influence of enzyme complex more markedly, a lower level of cellulase (9.1 mg protein/g glucan), near 30 FPU/g glucan was used for the following examination. T. reesei has long been used in industry widely for its highly productive and powerful destroyers of crystalline cellulose [14]. However, the level of BG activity of T. reesei is low, leading to incomplete conversion of cellobiose, which inhibits the cellulose conversion [15], to glucose in the cellulose hydrolysis process.…”

Section: Effect Of Cellulase Loadingmentioning

confidence: 99%

Enhanced Enzymatic Hydrolysis of Lignocellulose by Optimizing Enzyme Complexes

Zhang

et al. 2009

Appl Biochem Biotechnol

116

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To enhance the conversion of the cellulose and hemicellulose, the corncob pretreated by aqueous ammonia soaking was hydrolyzed by enzyme complexes. The saturation limit for cellulase (Spezyme CP) was determined as 15 mg protein/g glucan (50 filter paper unit (FPU)/g glucan). The accessory enzymes (beta-glucosidase, xylanase, and pectinase) were supplemented to hydrolyze cellobiose (cellulase-inhibiting product), hemicellulose, and pectin (the component covering the fiber surfaces), respectively. It was found that beta-glucosidase (Novozyme 188) loading of 1.45 mg protein/g glucan [30 cellobiase units (CBU)/g glucan] was enough to eliminate the cellobiose inhibitor, and 2.9 mg protein/g glucan (60 CBU/g glucan) was the saturation limit. The supplementation of xylanase and pectinase can increase the conversion of cellulose and hemicellulose significantly. The yields of glucose and xylose enhanced with the increasing enzyme loading, but the increasing trend became low at high loading. Compared with xylanase, pectinase was more effective to promote the hydrolysis of cellulose and hemicellulose. The supplementation of pectinase with 0.12 mg protein/g glucan could increase the yields of glucose and xylose by 7.5% and 29.3%, respectively.

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“…Although these promoters are 10-to 20-fold less active than the cbh1 promoter, they are still 50-to 100-fold stronger than the promoter of the phosphoglycerate kinase 1 gene (pgk1). 18) In T. reesei, one of the major drawbacks in cellulosic biomass degradation is the low level of -glucosidase activity, 19,20) which leads to incomplete conversion of cellobiose to glucose during the hydrolysis of cellulose. To overcome this disadvantage, cellulase preparations of T. reesei must be supplemented with -glucosidase from other sources to increase the rate and extent of cellulose hydrolysis.…”

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confidence: 99%