Effect of pretreatment and enzymatic hydrolysis of wheat straw on cell wall composition, hydrophobicity and cellulase adsorption

Toward combined delignification and saccharification of wheat straw by a laccase-containing designer cellulosome

“…Lignin acts as a physical barrier that restricts the access of hydrolytic enzymes to cellulose and hemicellulose components of the plant cell wall. Moreover, it has been shown that cellulases have a tendency to bind lignin in a nonreversible manner (48)(49)(50)(51), thus limiting their availability in solution. Thermochemical pretreatment processes that are used for removal of the lignin component before cellulose degradation tend to be expensive, slow, and relatively inefficient.…”

Reduction of surface area of lignin improves enzymatic hydrolysis of cellulose from hydrothermally pretreated wheat straw

“…Lignin has been said to undergo both depolymerization and repolymerization, 7 the rst resulting from cleavage of aryl ether bonds under acidic conditions. 8 Although degradation of cellulose does not usually occur in AH, 7 hemicellulose degradation can be drastic. The degradation products take part in further reactions, which in acid-catalyzed conditions generate so-called pseudo-lignin 9 that has been suggested to impede enzymatic hydrolysis of pretreated lignocellulosics.…”

Autohydrolysis and aqueous ammonia extraction of wheat straw: effect of treatment severity on yield and structure of hemicellulose and lignin

“…An earlier study compared yields of thioethylated lignin monomers released by thioacidolysis of native wheat straw and solid residues from acid-impregnated steam-exploded wheat straw, and found 77% decrease in lignin units only linked by aryl ether bonds. 26 Even though acidity in the AH liquors was lower compared to the pretreatment catalyzed by sulfuric acid, fragmentation of aryl ether linkages by acidolysis and condensation of lignin are expected to be the main reaction mechanisms in both media. 26 The resulting aqueous ammonia extracts likely contained varying proportions of "pseudolignin".…”

“…26 Even though acidity in the AH liquors was lower compared to the pretreatment catalyzed by sulfuric acid, fragmentation of aryl ether linkages by acidolysis and condensation of lignin are expected to be the main reaction mechanisms in both media. 26 The resulting aqueous ammonia extracts likely contained varying proportions of "pseudolignin". Interestingly, a polymeric product from the acid-catalyzed homopolymerization of furfural has been shown to have weight average molar mass of 1700 g mol À1 , 22 almost similar to the M w values of the aqueous ammonia extracts aer the high severity (log R 0 $ 4.1) AH treatments (Fig.…”