Enzymatic degradation of algal 1,3-xylan: from synergism of lytic polysaccharide monooxygenases with β-1,3-xylanases to their intelligent immobilization on biomimetic silica nanoparticles.

Lytic polysaccharide monooxygenases (LPMOs) with synergistic effect on polysaccharide hydrolase represent a revolution in biotechnology, which may accelerate the conversion of biomass to the second-generation biofuels. Discovering more hydrolases that have synergism with LPMOs will considerably expand the knowledge and application of biomass degradation. The LPMOs named CgAA9 were verified to exhibit 1.52-fold synergism when incubated with β-1,3-xylanase at a molar ratio of 3:1. The ion chromatography results proved that CgAA9 did not alter the endogenous hydrolysis mode of β-1,3-xylanase. Meanwhile, to decrease the operational cost of enzymes, a novel strategy for immobilizing LPMOs and β-1,3-xylanases based on the biomimetic silica nanoparticles was developed. It enabled preparation of immobilized enzymes directly from the cell lysate. The immobilization efficiency and activity recovery reached 84.6 and 81.4%. They showed excellent reusability for 12 cycles by retaining 68% of initial activity. The optimum temperature for both free and immobilized biocatalyst were 40 and 37 °C, indicating they were ideal candidates for typical simultaneous saccharification and fermentation (SSF) in ethanol production from algea biomass. This was the first report on the synergy between LPMOs and β-1,3-xylanase, and the strategy for enzyme self-immobilization was simple, timesaving, and efficient, which might have great potentials in algae biomass hydrolysis. KEY POINTS: • The lytic polysaccharide monooxygenases (LPMOs) from Chaetomium globosum were firstly verified to boost the hydrolysis of β-1,3-xylanases for β-1,3-xylan. • A novel strategy for simple preparation of SpyCather-modifed silica nanopartilcles and intelligent immobilization of target enzymes from the cell lysate was proposed. • The immobilized LPMOs and β-1,3-xylanases could be reasonable alternatives for typical simultaneous saccharification and fermentation (SSF) in manipulation of algae biomass.