Key metabolism pathways and regulatory mechanisms of high polysaccharide yielding in Hericium erinaceus

Abstract

Background Hericium erinaceus, a rare edible and medicine fungus, is widely used in the food and medical field. H. erinaceus polysaccharide is the main bioactive compound that exerts high bioactive value in the medical and healthcare industries. Results Here, we obtained two mutated strains (HEB and HEC) with high polysaccharide yield using ARTP mutagenesis from the original H. erinaceus strain HEA which genome was also reported 38.16 Mb, encoding 9,780 predicted genes by single-molecule, real-time sequencing technology. The polysaccharide content in the fermented mycelia of HEB and HEC was improved 23.25% and 47.45%, and a new β-glucan fraction with molecular weight 1.056 × 106 Da was produced in HEC. The phylogenomic analysis showed that H. erinaceus had the closest evolutionary affinity with Dentipellis sp. Integrative analysis of transcriptome and proteomics showed the upregulation of the carbohydrate metabolism pathway modules in HEB and HEC, which might lead to the increased production of glucose-6P and, in turn promoted the repeating units synthesis of polysaccharide. qPCR and PRM analysis confirmed that most of the co-enriched and differentially co-expressed genes involved in carbohydrates metabolism shared a similar expression trend with the transcriptome and proteome data in HEB and HEC. Heatmap analysis showed a noticeably decreased protein expression profile of the RAS-cAMP-PKA pathway in HEC with a highly increased 47.45% of polysaccharide content. The S phase progression blocking experiment further verified that the RAS-cAMP-PKA pathway's dysfunction might promote high polysaccharide and β-glucan production in the mutant strain. Conclusions The study revealed the main mechanism of the increased polysaccharide synthesis induced by ARTP mutagenesis and explored the key genes and pathways of polysaccharide synthesis.