Adding bamboo charcoal powder to Shiraia bambusicola preculture improves hypocrellin A production

Abstract

Hypocrellin A (HA), a photodynamic therapy (PDT) photosensitizer for cancers and viruses, is a perylenequinone pigment from the fruiting bodies of a bamboo pathogenic Shiraia bambusicola. Due to the limitation of the supply of wild Shiraia fruiting bodies and the complex chemosynthesis of HA, mycelium culture is becoming a biotechnological alternative for HA production. In this study, the novel approach recruited the addition of bamboo charcoal powder (BCP) (Ø2.3-5.5 μm) in preculture of S. bambusicola to stimulate HA production. BCP decreased the size of S. bambusicola pellets, enhanced the oxygen and sugar consumption, and increased the pH value of the broth of the production culture without any fungal growth retardation. The highest HA production (604.81 mg/L) was achieved when BCP at 2.0 g/L was added in the preculture. BCP treatment not only increased HA content in mycelia by 44.9-265.5%, but promoted its exudation to the medium by 57.0-160.5%, compared with the control respectively. Further analysis revealed that BCP treatment could induce the generation of reactive oxygen species (ROS) and occurrence of cell apoptosis in the pellets. The BCP addition up-regulated the gene expressions for HA biosynthesis and its exudation. Our study provides BCP as an inexpensive, bio-friendly and less toxic microparticle used in microparticle-enhanced cultivation (MPEC) to enhance the sustainable production of pharmaceutical important metabolites in mycelium cultures.