Heterologous Expression and Biochemical Characterization of a Novel Lytic Polysaccharide Monooxygenase from Chitinilyticum aquatile CSC-1.

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that catalyze the oxidative cleavage of recalcitrant polysaccharides. There are limited reports on LPMOs capable of concurrently catalyzing the oxidative cleavage of both cellulose and chitin. In this study, we identified and cloned a novel LPMO from the newly isolated bacterium Chitinilyticum aquatile CSC-1, designated as Ca LPMO10. When using 2, 6-dimethylphenol (2, 6-DMP) as the substrate, Ca LPMO10 exhibited optimal activity at 50 °C and pH 8, demonstrating good temperature stability at 30 °C. Even after a 6 h incubation at pH 8 and 30 °C, Ca LPMO10 retained approximately 83.03 ± 1.25% residual enzyme activity. Most metal ions were found to enhance the enzyme activity of Ca LPMO10, with ascorbic acid identified as the optimal reducing agent. Mass spectrometry analysis indicated that Ca LPMO10 displayed oxidative activity towards both chitin and cellulose, identifying it as a C1/C4-oxidized LPMO. Ca LPMO10 shows promise as a key enzyme for the efficient utilization of biomass resources in future applications.