Volatiles of fruiting body-associated No.24 stimulate fungal hypocrellin production.

Hypocrellins are major bioactive perylenequinones from fruiting bodies and have been developed as efficient photosensitizers for photodynamic therapy. is the second dominant genus inside fruiting bodies, but with less known actions on the host fungus In this work, the effects of bacterial volatiles from the -associated on fungal hypocrellin production were investigated. No.24 was the most active to promote significantly accumulation of perylenequinones including hypocrellin A (HA), HC, elsinochrome A (EA) and EC. Headspace analysis of the emitted volatiles revealed dimethyl disulfide as one of active compounds to promote fungal hypocrellin production. The bacterial volatiles induced an apoptosis in hyphal cell, which was associated with the generation of reactive oxygen species (ROS). ROS generation was proved to mediate the volatile-induced membrane permeability and up-regulation of gene expressions for hypocrellin biosynthesis. In the submerged volatile co-culture, the bacterial volatiles stimulated not only HA content in mycelia, but also HA secretion into the medium, leading to the enhanced HA production to 249.85 mg/L, about 2.07-fold over the control. This is the first report on the regulation of volatiles on fungal perylenequinone production. These findings could be helpful to understand the roles of bacterial volatiles in fruiting bodies and also provide new elicitation method using bacterial volatiles to stimulate fungal secondary metabolite production.