BackgroundThe combination of cellulase and lytic polysaccharide monooxygenase (LPMO) is known to boost enzymatic saccharification of cellulose. Although the synergy between cellulases (GH5, 6 or 7) and LPMOs (AA9) has been extensively studied, the interplay between other glycoside hydrolase and LPMO families remains poorly understood.ResultsIn this study, two cellulolytic enzyme-encoding genesSmBglu12AandSmLpmo10AfromStreptomyces megasporeswere identified and heterologously expressed inEscherichia coli. The recombinantSmBglu12A is a non-typical endo-β-1,4-glucanase that preferentially hydrolyzed β-1,3-1,4-glucans and slightly hydrolyzed β-1,4-glucans and belongs to GH12 family. The recombinantSmLpmo10A belongs to a C1-oxidizing cellulose-active LPMO that catalyzed the oxidation of phosphoric acid swollen cellulose to produce celloaldonic acids. Moreover, individualSmBglu12A andSmLpmo10A were both active on barley β-1,3-1,4-glucan, lichenan, sodium carboxymethyl cellulose, phosphoric acid swollen cellulose, as well as Avicel. Furthermore, the combination ofSmBglu12A andSmLpmo10A enhanced enzymatic saccharification of phosphoric acid swollen cellulose by improving the native and oxidized cello-oligosaccharides yields.ConclusionsThese results proved for the first time that the AA10 LPMO was able to boost the catalytic efficiency of GH12 glycoside hydrolases on cellulosic substrates, providing another novel combination of glycoside hydrolase and LPMO for cellulose enzymatic saccharification.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13068-023-02332-0.