Response mechanism of hypocrellin colorants biosynthesis by Shiraia bambusicola to elicitor PB90

The valuable medicine Shiraia bambusicola P. Henn. and its major active substance hypocrellin exert unique curative effects on skin diseases, diabetes, and cancers. The wild S. bambusicola is endangered due to its harsh breeding conditions and long growth cycle. It is one of the effective ways to utilize the resources sustainably to produce hypocrellin by fermentation of S. bambusicola. PB90 is a protein elicitor isolated from Phytophthora boehmeriae to induce the useful metabolites production in fungi. In this work, PB90 was selected to promote the synthesis hypocrellin by S. bambusicola. To evaluate the effect of PB90 on S. bambusicola, it was found that the induced cells showed decreased biomass, increased cell wall permeability, rapid induction of secondary metabolites, and significant increase of some enzyme activities, which confirmed a strong activation of phenylalanine/flavonoid pathways. Studies on signal molecules and gene expression level in S. bambusicola treated with PB90 have found that hydrogen peroxide (H2O2) and nitric oxide (NO) are necessary signal molecules involved in the synthesis of hypocrellin in elicited cells, and increased their signal levels through mutual reaction. We have showed for the first time, the response mechanism of hypocrellin biosynthesis from S. bambusicola to PB90, which may be not only establish a theoretical foundation for the application of PB90 to the mass production of S. bambusicola, but can also motivate further research on the application of PB90 to the conservation and sustainable utilization of other medical fungi.