Influences of substrate and tissue type on erinacine production and biosynthetic gene expression in Hericium erinaceus

Alongside the absence of detectable erinacines within fruit body samples, eri gene transcripts were consistently downregulated in the fruit body compared to the mycelium, particularly at early stages of the biosynthetic pathway. Substrate composition is a critical factor in production of erinacines by H. erinaceus, and large differences in mycelial erinacine content can occur without significant differences in expression of eri genes. Our data support the hypothesis that production of fungal secondary metabolites can be influenced by tissue type and substrate components, and that the expression of eri genes is enriched in the mycelium when compared to the fruit body.