Improving extracellular production of Serratia marcescens lytic polysaccharide monooxygenase CBP21 and Aeromonas veronii B565 chitinase Chi92 in Escherichia coli and their synergism.

Lytic polysaccharide monooxygenases (LPMOs) can oxidize recalcitrant polysaccharides and boost the conversion of the second most abundant polysaccharide chitin by chitinase. In this study, we aimed to achieve the efficient extracellular production of Serratia marcescens LPMO CBP21 and Aeromonas veronii B565 chitinase Chi92 by Escherichia coli. Twelve signal peptides reported with high secretion efficiency were screened to assess the extracellular production efficiency of CBP21 and Chi92, with glycine used as a medium supplement. The results showed that PelB was the most productive signal peptide for the extracellular production of CBP21 and Chi92 in E. coli. Furthermore, CBP21 facilitated the degradation of the three chitin substrates (colloidal chitin, β-chitin, and α-chitin) by Chi92. This study will be valuable for the industrial production and application of the two enzymes for chitin degradation.