Functional characterization of a lytic polysaccharide monooxygenase EbLPMO10A that contributes to β-chitin degradation by chitinase

The conversion of β-chitin, an abundant polysaccharide in cephalopod seafood byproducts, into high-value N-acetyl chitooligosaccharides (NCOSs) is crucial for the functional food and pharmaceutical industries. Lytic polysaccharide monooxygenases (LPMOs) oxidatively degrade insoluble polysaccharides and promote biomass degradation by hydrolases. However, the existence of LPMOs that specifically act on β-chitin remains unclear. In the study, we recombinantly expressed a novel AA10 LPMO, EbLPMO10A, from Enterobacteriaceae bacterium BIT-l23, which specifically oxidized β-chitin and was inactive against α-chitin. The oxidative depolymerization of β-chitin by EbLPMO10A exhibited a unique explosive granulation and enhanced regional activity of hydrolases. Combining 5.0 μM EbLPMO10A with 1.0 μM ChiB (chitinase from Serratia marcescens) achieved 76.74 % conversion of β-chitin to (GlcNAc)₂, a 4.46-fold increase over ChiB alone. These promising results suggest that EbLPMO10A may benefit the targeted conversion of β-chitin in the food and chemical industries.