Reducing non-productive adsorption of cellulase and enhancing enzymatic hydrolysis of lignocelluloses by noncovalent modification of lignin with lignosulfonate

Abstract

Four fractions of one commercial sodium lignosulfonate (SXP) with different molecular weight (MW) and anionic polymers were studied to reduce non-productive adsorption of cellulase on bound lignin in a lignocellulosic substrate. SXP with higher MW had stronger blocking effect on non-productive adsorption of a commercial Trichoderma reesi cellulase cocktail (CTec2) on lignin measured by quartz crystal microgravimetry with dissipation monitoring. Linear anionic aromatic polymers have strong blocking effect, but they would also reduce CTec2 adsorption on cellulose to decrease the enzymatic activity. The copolymer of lignin and polyethylene glycol (AL-PEG1000) has strong enhancement in enzymatic hydrolysis of lignocelluloses, because it not only improves the cellulase activity to cellulose, but also blocks the non-productive cellulase adsorption on lignin. Apart from improving the cellulase activity to cellulose, the enhancements of enzymatic hydrolysis of lignocellulose by adding AL-PEG1000 and SXPs are the result of the decreased cellulase non-productive adsorption on lignin.

Keywords: AFM; AL-PEG1000; ASP; Adsorption; CBM; CTec2; Cellulase; Enzymatic hydrolysis; FDN; LS; Lignin; Lignosulfonate; MW; PEG; QCM-D; SAF; SED; SXP; atomic force microscope; carbohydrate-binding module; commercial Trichoderma reesi cellulase cocktail; copolymer of lignin and polyethylene glycol; formaldehyde naphthalene sulfonate condensate; lignosulfonate; molecular weight; polyethylene glycol; quartz crystal microgravimetry with dissipation monitoring; substrate enzymatic digestibility; sulfanilic acid–phenol–formaldehyde condensate; sulfonated acetone–formaldehyde condensate; the commercial sodium lignosulfonate.