Abstract
BackgroundThe 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.ResultsIn 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.ConclusionsTaken 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.
Highlights
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
Taken 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
Effects of the addition of Mn2+ on growth and cellulase production of T. reesei To determine how Mn2+ influences the hyphal growth, T. reesei Rut-C30 strains were cultured on MM plates supplemented with different concentrations of Mn2+ (0, 1, 10, 20, and 40 mM final concentration) and 2% glucose as the sole carbon source
Summary
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. A common host cited for the production of cellulases and hemicellulases is the saprotrophic, filamentous fungus Trichoderma reesei, which is well known for its excellent ability to secrete a broad range of cellulases at very high levels [1,2,3,4]. In Aspergillus nidulans, high levels of M n2+ can induce an increase in intracellular Ca2+ levels, which leads to the nuclear accumulation of CrzA [18, 19]. These observations suggest that C a2+ and Mn2+ have relevant impacts on the cellular physiology and metabolism of various organisms. The ability to sense and respond to Mn2+ by the production of import and efflux systems to maintain Mn2+
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
