Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Biology

Supervisor

Thorn, R. Greg

Abstract

The genus Hericium contains species demonstrated to produce bioactive secondary metabolites with potential medical applications. Previous phylogenies of the genus Hericium based on the internal transcribed spacer (ITS) region struggle to support monophyly at the species level, hindering biochemical research efforts. Using concatenated sequence data from ITS, the large ribosomal subunit (LSU), translation elongation factor 1-alpha (tef1) and RNA polymerase subunit 2 (rpb2) genes, Hericium species from North America and key taxa from Europe were resolved as monophyletic groups. Several species of Hericium from North America also demonstrated production of erinacine A, a secondary metabolite with nerve-growth factor stimulatory activity, and liquid culture conditions were modified for enhanced erinacine A biosynthesis in each species. Together with clear distinction of the species in Hericium, the findings presented herein will contribute to natural products research and medical applications of these edible and medicinally valuable mushrooms.

Summary for Lay Audience

Hericium is a genus of fungi that produce edible fruiting bodies (mushrooms) with a history of use in East Asian medical traditions. Evidence of their beneficial health effects has increased the demand for the cultivated species, H. erinaceus, known locally as the Lion’s Mane mushroom. However, prior works have shown that there are uncertainties in the correct names used for species in the genus and how these species are related to each other.

To better understand the evolutionary relationships in Hericium, I analyzed data from several genes of various Hericium species. The results of this analysis were significantly more informative of species boundaries than previous studies that used only a single gene. I also found that a species previously known as H. erinaceus is actually four distinct species.

Hericium mushrooms are considered medicinal mushrooms as these fungi are sources of bioactive compounds. One of the compounds produced by Hericium, erinacine A, is being considered as a potential therapeutic tool in neurological diseases. However, the production of erinacine A is only known from a few Hericium species. In this study, I found evidence of erinacine A production in several species of which erinacine A production was previously unknown. I also aimed to maximize erinacine A production in each species. This study provides evidence that several Hericium species may be used as sources for erinacine A in medical research and describes methods to optimize its production in those species.

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