The gene lpmo1 encoding Penicillium verruculosum lytic polysaccharide monooxygenase (PvLPMO9A) was sequenced and homologously overexpressed in P. verruculosum B1-537 (ΔniaD) auxotrophic strain under the control of the cbh1 gene promoter in combination with either the cbh1 signal sequence (sCBH1-X series of samples) or the native lpmo1 signal sequence (sLPMO1-X series). Three enzyme samples of the sCBH1-X series were characterized by a lower overall content of cellobiohydrolases (CBHs: 26-45%) but slightly higher content of endoglucanases (EGs: 17-23%) relative to the reference B1-537 preparation (60% of CBHs and 14% of EGs), while the PvLPMO9A content in them made up 9-21% of the total secreted protein. The PvLPMO9A content in four enzyme preparations of the sLPMO1-X series was much higher (30-57%), however the portion of CBHs in most of them (except for sLPMO1-8) decreased even to a greater extent (to 21-42%) than in the samples of the sCBH1-X series. Two enzyme preparations (sCBH1-8 and sLPMO1-8), in which the content of cellulases was substantially retained and the portion of PvLPMO9A was 9-30%, demonstrated the increased yields of reducing sugars in 48-h saccharification of Avicel and milled aspen wood: 19-31 and 11-26%, respectively, compared to the reference cellulase cocktail.
Keywords: Cellulase; Homologous expression; Lytic polysaccharide monooxygenase; Penicillium verruculosum; Saccharification.