Background The filamentous fungus Trichoderma reesei Rut-C30 is one of the most vital fungi for the production of cellulases, which can be used for biofuel production from lignocellulose. Nevertheless, the mechanism of transmission of external stimuli and signals in modulating cellulase production in T. reesei Rut-C30 remains unclear. Calcium is a known second messenger regulating cellulase gene expression in T. reesei.Results In this study, we found that a biologically relevant extracellular Mn2+ concentration markedly stimulates cellulase production, total protein secretion, and the intracellular Mn2+ concentration of Rut-C30, a cellulase hyper-producing strain of T. reesei. Furthermore, we identified two Mn2+ transport proteins, designated as TPHO84-1 and TPHO84-2, indicating that they are upstream in the signaling pathway that leads to cellulase upregulation. We also found that Mn2+ induced a significant increase in cytosolic Ca2+ concentration, and that this increased cytosolic Ca2+ might be a key step in the Mn2+-mediated regulation of cellulase gene transcription and production. The utilization of LaCl3 to block plasma membrane Ca2+ channels, and deletion of crz1 (calcineurin-responsive zinc finger transcription factor 1) to interrupt calcium signaling, showed that Mn2+ exerts the induction of cellulase genes via calcium channels and calcium signaling. To substantiate this, we identified a Ca2+/Mn2+ P-type ATPase, TPMR1, which could play a pivotal role in Ca2+/Mn2+ homeostasis and Mn2+ induction of cellulase genes in T. reesei Rut-C30.Conclusion sTaken together, our results revealed for the first time that Mn2+ stimulates cellulase production, and demonstrates that Mn2+ upregulates cellulase genes via calcium channels and calcium signaling. Our research also provides a direction to facilitate enhanced cellulase production by T. reesei.
Liu Shuai,Quan Lin,Yang Mei,Wang Dan,Wang Yong-Zhong
In this study, the effect of polyethylene glycol 8000 (PEG8000) stress on cellulase biosynthesis in Trichoderma reesei CICC2626 via calcium signaling was investigated, and a plausible mechanism by which intracellular Ca 2+ 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 T. reesei 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 2+ inhibitors and deletion of crz1 (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 T. reesei CICC2626. Moreover, this study also provides a novel inducer for enhanced cellulase production. Key points • Cellulase biosynthesis in Trichoderma reesei could be enhanced by PEG8000 • PEG8000 could induce a cytosolic Ca 2+ burst in Trichoderma reesei • The activated calcium signaling was involved in cellulase biosynthesis Graphical abstract
危险品化学品经营许可证（带存储）