Enhancement of the enzymatic cellulose saccharification by Penicillium verruculosum multienzyme cocktails containing homologously overexpressed lytic polysaccharide monooxygenase

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.