The Effect Of Ethanol Extract Of Gastrodia Elata On Submerged Fermentation Of Extracellular Polysaccharides From Grifola Frondosa And Its Mechanism

This article was aimed at studying the effect and mechanism of Rhizome gastrodia alcohol extract on the production of exopolysaccharides from Grifola frondosa.Including the effect of Rhizome gastrodia alcohol extract on mycelial growth,synthesis of exopolysaccharides and key enzyme activities of G.frondosa;the transcriptome of G.frondosa was sequenced and analyzed by bioinformatics and differentially expressed genes;the effect of Rhizome gastrodia alcohol extract and its characteristic components on the antioxidant activity of extracellular polysaccharides from G.frondosa.The main conclusions of this research as follows:The influence of Rhizome gastrodia alcohol extract on the synthesis of exopolysaccharides and the activity of key enzymes in G.frondosa.the results showed that the influence on mycelial growth and exopolysaccharide synthesis of G.frondos was obvious when the Rhizome gastrodia alcohol extract content was 7 g/L.Compared with the control group,the mycelial increased by 44.24% and the EPS increased by 37.98%.In addition,it could significantly increase the activities ofα-phosphoglucomutase and inhibit the activity of phospho-glucose isomerase,and the activities of the two key enzymes showed the highest enzyme activity on the 12 th day after fermentation.The transcriptome of G.frondosa was sequenced by high-throughput sequencing technology.A total of 74 575 910 reads and 10.4 G data were generated,which formed 18 077 Unigenes after de novo splicing.A total of 11 651 Unigenes were annotated in the Nr database.Among them,G.frondosa transcriptome had the most similar sequence(18.74%)to M.tumefaciens.A total of 8 332 Unigene were annotated in the GO database,which were divided into 3 major categories: molecular composition,molecular function and biological processes,including 59 branches.Compared with the KEGG database,5 200 Unigenes were annotated which belonged to 376 metabolic pathways.A total of 1 155 simple sequence repeat(SSR)loci werefound in 18 077 Unigenes,among which the highest repeat was single nucleotide whereas the repetition of hexanucleotide was the least,and the frequency of A/T was the highest.In this study,115 unigenes which have been annotated in the database of KEGG were related to the biosynthesis of polysaccharide by G.frondosa.These annotated Unigenes and the information about them can lay the foundation for further studies on polysaccharide metabolism pathways and related functional genes in G.frondosa.Differential gene screening: 181 differentially expressed genes were screened by FPKM value method,which 87 genes were up-regulated and 94 genes were down-regulated in the ethanol extract group;Gene ontology functional enrichment analysis results showed that a total of 75 differentially expressed genes were significantly enriched,and in the enriched first 20 GO terminals which had significant differences,in the molecular function class,genes expression associated with aromatic alcohol dehydrogenase(NADP +)activity were up-regulated,genes associated with polygalacturonase activity were down-regulated;in biological processes,genes expression correlated with salicylic acid,galacturonic acid metabolism,pectin metabolism,and pectin catabolism were down-regulated;the KEGG functional enrichment analysis results showed that 13 differentially expressed genes were annotated and involved 22 metabolic pathways.Among which the genes related to the pyruvate metabolism pathway and polysaccharide degradation pathway in the group of the rhizome gastrodia were down-regulated,which may be the mechanism that the Rhizome gastrodia alcohol extract can promote the synthesis of exopolysaccharides.The effect of the Rhizome gastrodia alcohol extract and its characteristic components on the antioxidant activity of extracellular polysaccharides from G.frondosa.The results showed that the antioxidant capacity(DPPH scavenging radicals,hydroxyl scavenging radicals and reducing power)of the experimental group and the control group were lower than the Vc group,and the Rhizome gastrodia alcoholextract and its characteristic components could significantly promote the antioxidant activity of exopolysaccharides of G.frondosa.And the p-Hydroxybenzaldehyde had the most obvious effect on the DPPH radical scavenging ability and hydroxyl radical scavenging ability of the exopolysaccharide from G.frondosa;the Rhizome gastrodia alcohol extract had the most obvious effect on the reducing power of exopolysaccharide from G.frondosa.