Chitin Biodegradation by Lytic Polysaccharide Monooxygenases from Streptomyces coelicolor In Vitro and In Vivo

Lytic polysaccharide monooxygenases (LPMOs) have the potential to improve recalcitrant polysaccharide hydrolysis by the oxidizing cleavage of glycosidic bond.Streptomycesspecies are major chitin decomposers in soil ecological environments and encode multiplelpmogenes. In this study, we demonstrated that transcription of thelpmogene,Sclpmo10G, in theStreptomyces coelicolorA3(2) (ScA3(2)) strain is strongly induced by chitin. TheScLPMO10G protein was further expressed inEscherichia coliand characterized in vitro. TheScLPMO10G protein showed oxidation activity towards chitin. Chitinase synergy experiments demonstrated that the addition ofScLPMO10G resulted in a substantial in vitro increase in the reducing sugar levels. Moreover, in vivo the LPMO-overexpressing strainScΔLPMO10G(+) showed stronger chitin-degrading ability than the wild-type, leading to a 2.97-fold increase in reducing sugar level following chitin degradation. The total chitinase activity ofScΔLPMO10G(+) was 1.5-fold higher than that ofScA3(2). In summary,ScLPMO10G may play a role in chitin biodegradation inS. coelicolor, which could have potential applications in biorefineries.Keywords:lytic polysaccharide monooxygenases;transcription;expression;Streptomyces coelicolorA3(2);chitin biodegradation