Improved ganoderic acids production in Ganoderma lucidum by wood decaying components

Yanru Hu,Zengyan Gao,Jiawei Li,Biaobiao Luo,Xuebo Hu,Shakeel Ahmed,Xiaohua Li,Qiyun Zhang

doi:10.1038/srep46623

Abstract

Ganoderma lucidum is a legendary Traditional Chinese Medicine (TCM) over a few thousands of years and one kind of its major active components are Ganoderic acids (GAs). GAs are largely produced in the mushroom primordium and fruiting body but much less in mycelium stage. However, little is known on the underlying regulatory mechanism. As a saprophytic fungus, G. lucidum solely obtains nutrients by wood decaying. Wood in general contains sophisticated chemical components with diverse structural units. To explore a strategy that extensively leads to GAs induction in the submerged liquid fermentation, all chemical components that might be possibly from the wood decaying were tested individually as GAs inducers. It was found that GAs production increased 85.96% by 1.5% microcrystalline cellulose (MCC) and 63.90% by 0.5% D-galactose. The transcription level of a few rate-limiting or chemically diverting enzymes responsible for GAs biosynthesis was greatly induced by MCC and D-galactose. The concentration and time-course titration study indicated that these two chemicals might not be utilized as carbon sources but they played a comprehensive role in the secondary metabolites synthesis. Our data indicated that MCC and D-galactose might be further industrialized for higher GAs production in G. lucidum in submerged fermentation.

Highlights

Ganoderma lucidum is a legendary Traditional Chinese Medicine (TCM) over a few thousands of years and one kind of its major active components are Ganoderic acids (GAs)
Chemicals tested for GAs induction were microcrystalline cellulose (MCC) and its degradative product D-cellobiose, lignin and its degradation product coniferyl alcohol and various hemicellulose degradation products, including D-galactose, L-arabinose, D-xylose and D-rhamnose, D-mannose, glucan hyaluronic acid and algin sodium mannuronic acid
The result showed that the GAs production increased along with MCC dosage, while D-cellobiose had no effect on GAs biosynthesis and G. lucidum growth at a concentration of 0.1%, 0.5% and 0.25% (Fig. 2a–c)

Summary

Introduction

Ganoderma lucidum is a legendary Traditional Chinese Medicine (TCM) over a few thousands of years and one kind of its major active components are Ganoderic acids (GAs). To explore a strategy that extensively leads to GAs induction in the submerged liquid fermentation, all chemical components that might be possibly from the wood decaying were tested individually as GAs inducers. Our data indicated that MCC and D-galactose might be further industrialized for higher GAs production in G. lucidum in submerged fermentation. The most important bioactive products of G. lucidum, as claimed by numerous studies[9,10,11,12,13,14,15,16], are Ganoderic acids (GAs), which belong to a class of oxygenated C30 lanostane-type triterpenoids (Fig. 1). In order to enhance the oxygen utilization of G.lucidum, mushroom transformed with Vitreoscilla hemoglobin gene showed up to two times higher GAs production over the non-transgenic control[28].

Methods

Results

Conclusion