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

The genome of H. erinaceus original strain HEA was reported 38.16 Mb, encoding 9,780 predicted genes by single-molecule, real-time sequencing technology. The phylogenomic analysis showed that H. erinaceus had the closest evolutionary affinity with Dentipellis sp. The polysaccharide content in the fermented mycelia of mutated strains HEB and HEC, which obtained by ARTP mutagenesis in our previous study, was improved by 23.25% and 47.45%, and a new β-glucan fraction with molecular weight 1.056×10^6 Da was produced in HEC. Integrative analysis of transcriptome and proteomics showed the upregulation of the carbohydrate metabolism pathway modules in HEB and HEC might lead to the increased production of glucose-6P and promote the repeating units synthesis of polysaccharides. qPCR and PRM analysis confirmed that most of the co-enriched and differentially co-expressed genes involved in carbohydrate 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 HEC. In this study, we reported the original strain genome of H. erinaceus using a single molecule, real-time sequencing technology, and multi-omics analysis was carried out between mutant strains obtained by ARTP mutagenesis and the original strain. Multi-omics analysis indicated that the increased carbohydrate metabolism and the production of glucose-6P constitute the basis of high polysaccharide yield in ARTP mutated strain. Furthermore, the RAS-cAMP-PKA pathway's decreased activity might promote high polysaccharide and β-glucan production through the block of S phase progression. The study revealed the mechanism of the increased polysaccharide synthesis induced by ARTP mutagenesis associated with carbohydrate metabolism and glucose signaling regulation dysfunction and provided the critical theoretical and practical basis for polysaccharide production in H. erinaceus.