The effect of isolated lignins, obtained from a range of pretreated lignocellulosic substrates, on enzymatic hydrolysis

Abstract

The influence of the residual lignin remaining in the cellulosic rich component of pretreated lignocellulosic substrates on subsequent enzymatic hydrolysis was assessed. Twelve lignin preparations were isolated by two isolation methods (protease treated lignin (PTL) and cellulolytic enzymatic lignin (CEL)) from three types of biomass (corn stover, poplar, and lodgepole pine) that had been pretreated by two processes (steam and organosolv pretreatments). Comparative analysis of the isolated lignin showed that the CEL contained lower amounts of carbohydrates and protein than did the PTL and that the isolated lignin from corn stover contained more carbohydrates than did the lignin derived from the poplar and lodgepole pine. The lower yields of acid insoluble lignin (AIL) obtained from the corn stover when using the PTL method indicated that the lignin from the corn stover had a higher hydrophilicity than did the lignin from the poplar and lodgepole pine. The isolated lignin preparations were added to the reaction mixture containing crystalline cellulose (Avicel) and their possible effects on enzymatic hydrolysis were assessed. It was apparent that the lignin isolated from lodgepole pine and steam pretreated poplar decreased the hydrolysis yields of Avicel, whereas the other isolated lignins did not appear to decrease the hydrolysis yields significantly. The hydrolysis yields of the pretreated lignocellulose and those of Avicel containing the PTL showed good correlation, indicating that the nature of the residual lignin obtained after pretreatment significantly influenced hydrolysis.

Study of the Difference between Enzyme Adsorption onto Hydrotropic and Alkali Lignin Separated from Eucalyptus and Bamboo

“…This implied that the hydrophobicity was the main factor that influenced the adsorption of cellulase onto the lignin samples. The same conclusion was reached in previous studies (Gessner et al 2000;Nakagame et al 2010Nakagame et al , 2011aRahikainen et al 2013). The surface charges of the Eusxs, Bsxs, EuA, and BA were -0.78 mmol/g, -1.47 mmol/g, -1.0 mmol/g, and -0.85 mmol/g, respectively.…”

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

“…The isolated lignins were mixed with crystalline cellulose (Avicel) to assess the effect of lignin on enzymatic hydrolysis. It was found that the lignin isolated from lodgepole pine and steam-pretreated poplar decreased the hydrolysis yields of Avicel significantly, which provided evidence that supported the supposition of non-productive adsorption of enzymes onto lignins (Nakagame et al 2010). Overall, lignin presents a unique challenge to the pulping and biofuel processing industries in that it is fairly recalcitrant towards degradation reactions.…”

Silencing CAFFEOYL SHIKIMATE ESTERASE Affects Lignification and Improves Saccharification in Poplar

“…One of the major factors contributing to biomass recalcitrance is the presence of lignin, an aromatic polymer that provides strength and hydrophobicity to the cell wall. Lignin hinders the efficient enzymatic depolymerization of cellulose and hemicellulose into fermentable sugars by immobilizing the hydrolytic enzymes and physically limiting the access to their polysaccharide substrates (Chang and Holtzapple, 2000;Berlin et al, 2006;Nakagame et al, 2010;Guo et al, 2014). Although a number of pretreatments have been developed to remove lignin and consequently lower biomass recalcitrance, the pretreatment is still a relatively expensive step in the conversion process (Zhao et al, 2012b;Vanholme et al, 2013b).…”