In-depth recognition of mixed surfactants maintaining the enzymatic activity of cellulases through stabilization of their spatial structures

Abstract

Mixed surfactants improve the enzymatic hydrolysis of lignocellulosic substrates by enhancing cellulase stability against heat, pH, shear, and air-liquid interface stress. Under conditions of multiple factorial stresses (50 °C, pH 4.8, 180 rpm, and 15.5 cm² air-liquid interface), cellulase with ternary surfactants (Tween 60/Triton X-114/CTAB, the molar ratio 14:5.5:1) retained 84 % of its activity after 48 h of incubation, representing 1.15 and 1.29 folds that of the cellulase activity with the single Tween 60 and with no surfactants, respectively. This is attributed to the fact that ternary surfactants possess better rheology modulation and air-liquid interface competitiveness. In addition, the computational approach demonstrated that the ternary surfactants were capable of forming stronger hydrophobic and hydrogen-bond interactions with cellulase enzymes, thus maintaining its secondary structure and preventing the detrimental α-helix to β-sheet transformation known to compromise cellulase activity. This synergy offers valuable insights into surfactant-cellulase interactions and supports efficient enzymatic hydrolysis in biorefineries.

Keywords: Cellulase secondary structure; Cellulase stability; Enzymatic hydrolysis; Molecular interaction; Surfactants.