The effect of cellobiohydrolase 1 gene knockout for composition and hydrolytic activity of the enzyme complex secreted by filamentous fungus Penicillium verruculosum

The filamentous fungus Penicillium verruculosum is used as an industrial producer of cellulases and other enzymes and enzymatic complexes. Secreted cellobiohydrolases (CBHs) are the key components of the P. verruculosum enzyme complex because they can hydrolyse both amorphous and microcrystalline cellulose (MCC). CBHs cleave cellobiose residues from the ends of polymer molecules of native or partially hydrolysed cellulose. There are two CBH isoforms: CBH 1 (EC 3.2.1.176) attacks the cellulose molecule from the reducing end, while CBH 2 (EC 3.2.1.91) acts from the non-reducing end. In this study, the cbh1 gene encoding CBH 1 was knocked out by adapted CRISPR/Cas9 genome editing technology. As a result of the СBH 1 removal, the content of CBH 2, endoglucanase (EG), xylanase and β-glucosidase (BG) increased. However, this compensatory effect did not lead to an increase in hydrolytic efficiency in the saccharification of microcrystalline cellulose and pretreated aspen wood. • The CRISPR/Cas9 system was adapted to genome editing in Penicillium verruculosum . • The gene of major cellulolytic enzyme of the P. verruculosum , cbh1 , was knocked out. • The knockout of the cbh1 gene led to increase of other carbohydrases expression. • The Δcbh1 EP reduced its hydrolytic activity on MCC, but not on untreated aspen.