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Inhibition of cellulose enzymatic hydrolysis by laccase-derived compounds from phenols.

Biotechnology progress (2015-03-06)
Alfredo Oliva-Taravilla, Elia Tomás-Pejó, Marie Demuez, Cristina González-Fernández, Mercedes Ballesteros
ZUSAMMENFASSUNG

The presence of inhibitors compounds after pretreatment of lignocellulosic materials affects the saccharification and fermentation steps in bioethanol production processes. Even though, external addition of laccases selectively removes the phenolic compounds from lignocellulosic prehydrolysates, when it is coupled to saccharification step, lower hydrolysis yields are attained. Vanillin, syringaldehyde and ferulic acid are phenolic compounds commonly found in wheat-straw prehydrolysate after steam-explosion pretreatment. These three phenolic compounds were used in this study to elucidate the inhibitory mechanisms of laccase-derived compounds after laccase treatment. Reaction products derived from laccase oxidation of vanillin and syringaldehyde showed to be the strongest inhibitors. The presence of these products causes a decrement on enzymatic hydrolysis yield of a model cellulosic substrate (Sigmacell) of 46.6 and 32.6%, respectively at 24 h. Moreover, a decrease in more than 50% of cellulase and β-glucosidase activities was observed in presence of laccase and vanillin. This effect was attributed to coupling reactions between phenoxyl radicals and enzymes. On the other hand, when the hydrolysis of Sigmacell was performed in presence of prehydrolysate from steam-exploded wheat straw a significant inhibition on enzymatic hydrolysis was observed independently of laccase treatment. This result pointed out that the other components of wheat-straw prehydrolysate are affecting the enzymatic hydrolysis to a higher extent than the possible laccase-derived products.

MATERIALIEN
Produktnummer
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Produktbeschreibung

Sigma-Aldrich
Saccharose, for molecular biology, ≥99.5% (GC)
Sigma-Aldrich
Saccharose, ≥99.5% (GC)
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Saccharose, ≥99.5% (GC), BioXtra
Sigma-Aldrich
Saccharose, BioUltra, for molecular biology, ≥99.5% (HPLC)
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Saccharose, ≥99.5% (GC), BioReagent, suitable for cell culture, suitable for insect cell culture
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Saccharose, ≥99.5% (GC)
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L-Lysin -monohydrochlorid, from non-animal source, meets EP, JP, USP testing specifications, suitable for cell culture, 98.5-101.0%
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trans-Ferulasäure, 99%
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Saccharose, ≥99.5% (GC), Grade II, suitable for plant cell culture
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Saccharose, Grade I, ≥99% (GC), suitable for plant cell culture
Sigma-Aldrich
Vanillin, ReagentPlus®, 99%
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Syringaldehyd, 98%
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Vanillin, natural, ≥97%, FCC, FG
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Saccharose, meets USP testing specifications
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Vanillin, ≥97%, FCC, FG
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trans-Ferulasäure, ≥99%
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Saccharose, ACS reagent
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Sigmacell Cellulose, Type 50, 50 μm
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Saccharose, puriss., meets analytical specification of Ph. Eur., BP, NF
Sigma-Aldrich
L-Lysin -monohydrochlorid, reagent grade, ≥98% (HPLC)
Sigma-Aldrich
Syringaldehyd, ≥98%, FG
Sigma-Aldrich
L-Lysin -monohydrochlorid, BioUltra, ≥99.5% (AT)