Mn2+ modulates the production of mycophenolic acid in Penicillium brevicompactum NRRL864 via reactive oxygen species signaling and the investigation of pb-pho

Although Penicillium brevicompactum is a widely used commercial strain for the manufacture of mycophenolic acid, there are few findings of Ca²⁺, Mn²⁺, and reactive oxygen species (ROS) interaction. Metal ions play a crucial role in physiological metabolism. Calcium, as the important second messenger, influences fungus growth, virulence, and stress responses. The concentration of cytosolic Ca²⁺ was influenced by the Mn²⁺, which demonstrated the crosstalk between calcium and manganese. In the previous study, the crosstalk between calcium and ROS has been discovered and verified, which modified the secondary metabolism and enhanced the yield of MPA (Mycophenolic Acid). A higher concentration of Mn²⁺ in the fermentation broth causes an increase in cytoplasmic Ca²⁺ and ROS (Reactive Oxygen Species), enhancing the yield of MPA by about 20 % higher and disclosing the cascade regulation with the Mn²⁺, Ca²⁺, and ROS. To be more specific, the intracellular concentration of ROS at 6 mM Mn²⁺ is about 1.5 times higher than that at 0.6 mM. Furthermore, we identify an Mn²⁺ transport protein, designated as Pb–PHO, which shows 71.2 % identity to the inorganic phosphate transporter PHO84 (Q0CBJ6) from Aspergillus terreus. At the same time, the △Pb-pho exhibits damage to the cell wall integrity, while the OE-pho displays a more normal phenotype at high osmotic stress. The high-affinity Ca²⁺ channel, Pb–CCH, is examined via knockdown to demonstrate the crosstalk between Mn²⁺ and Ca²⁺. The results show that the addition of Mn²⁺ remits the negative influence of pb-cch knockdown and the addition of Ca²⁺ remits the negative influence of pb-pho knockdown, demonstrating the relationship between cytoplasmic Mn²⁺ and Ca²⁺. Taken together, our results demonstrate the mechanism of a manganese-induced cascade of manganese-calcium-ROS and reveal a signal pathway-relative method to illustrate the manganese-induced increase of MPA production in Penicillium brevicompactum. Furthermore, we discover and identify an Mn²⁺ transport protein, Pb–PHO, which is subcellular localized at the plasma membrane and proved to affect the cell wall integrity.