초록
<P>Abstract<P>In this study, the effect of polyethylene glycol 8000 (PEG8000) stress on cellulase biosynthesis in <I>Trichoderma reesei</I> CICC2626 via calcium signaling was investigated, and a plausible mechanism by which intracellular Ca<SUP>2+</SUP> regulates the transcription of cellulase genes was proposed. The results indicated that the total cellulase (filter paper-hydrolyzing activity [FPase]), endoglucanase (carboxymethyl cellulase activity [CMCase]), and β-glucosidase activities of the strain were 1.3-, 1.2-, and 1.3-fold higher than those of the control (no PEG8000 addition) at a final concentration of 1.5% (w/v) PEG8000. Moreover, the transcriptional levels of cellulase genes, protein concentrations, and biomass increased. With the synergistic use of commercial cellulase and <I>T. reesei</I> CICC2626 cellulase to hydrolyze alkali-pretreated rice straw, the released reducing sugar concentration reached 372.7 mg/g, and the cellulose content (22.7%, 0.32 g) was significantly lower than the initial content (62.5%, 1.88 g). Transcriptome data showed that 12 lignocellulose degradation-related genes were significantly upregulated in the presence of 1.5% PEG8000. Furthermore, the addition of Ca<SUP>2+</SUP> inhibitors and deletion of <I>crz1</I> (calcineurin-responsive zinc finger 1-encoding gene, which is related to the calcium signaling pathway) demonstrated that calcium signaling plays a dominant role in PEG8000-induced cellulase genes overexpression. These results revealed a link between PEG8000 induction and calcium signaling transduction in <I>T. reesei</I> CICC2626. Moreover, this study also provides a novel inducer for enhanced cellulase production.</P></P><P>Key points<P>• <I>Cellulase biosynthesis in Trichoderma reesei could be enhanced by PEG8000</I></P><P>• <I>PEG8000 could induce a cytosolic Ca</I><SUP><I>2+</I></SUP><I> burst in Trichoderma reesei</I></P><P>• <I>The activated calcium signaling was involved in cellulase biosynthesis</I></P></P><P>Graphical abstract</P>