Heterologous expression and characterization of a novel lytic polysaccharide monooxygenase from Natrialbaceae archaeon and its application for chitin biodegradation

Lytic polysaccharide monooxygenases could enhance the enzymatic conversion of recalcitrant polysaccharides by glycoside hydrolases. This study reports the expression and identification of a novel AA10 LPMO from Natrialbaceae archaeon , named Na LPMO10A, as a C1 oxidizer of chitin. The optimal temperature and pH for Na LPMO10A activity were 40 °C and 9.0, respectively, and Na LPMO10A exhibited high thermostability and pH stability under alkaline conditions. Na LPMO10A was also highly tolerant and stable when treated with high concentration of metal ions (1 M). Moreover, metal ions (Na + , K + , Ca 2+ and Mg 2+ ) significantly promoted Na LPMO10A activity and improved the saccharification efficiency of chitin by 22.6%, 45.9%, 36.7% and 53.9%, respectively, compared to commercial chitinase alone. Together, the findings of this study fill a gap in archaeal LPMO research, and for the first time demonstrate that archaeal Na LPMO10A could be a promising enzyme for improving saccharification under extreme condition, with potential applications in biorefineries.