Study On Physiological Characteristics,important Bioactive Compounds,the Multi-Omics Elucidation And Genetic Characterization Of Floccularia Luteovirens

Floccularia luteovirens is a unique and rare wild edible and medicinal fungus in Qinghai-Tibet Plateau.It has important research value and development prospects because of its high nutritional and medicinal value.Meanwhile,it received widespread attention in recent years.However,in the past few decades,the F.luteovirens had not been studied in depth.Consequently,this thesis was aimed to study the physiological characteristics,key bioactive compounds,multi-omics analysis and genetic characterization of F.luteovirens.The main results are summarized as follows.1.With electron microscopes,the microstructure of mycelia and spores of F.luteovirens were observed for the first time.The growth system of F.luteovirens mycelia under basic culture conditions was established to lay the foundation for subsequent research.It was found that selenium and different lights had inhibitory effects on the growth of mycelia and the synthesis of active substances.A method for cultivating F.luteovirens mycelia with airlift fermenter was established.It was found that wheat grains were suitable original culture media for artificial cultivation of F.luteovirens.2.This is the first report of the exopolysaccharides from the fermentation mycelia of F.luteovirens and two EPS fractions(ALF1 and ALF2)were obtained.The chemical characterizations,thermal properties and in vitro antioxidant activities of ALF1 and ALF2 were investigated.The average molecular mass of ALF1 was estimated to be2.836×10⁴ Da,while ALF2 was estimated to be 1.866×10⁴ Da.The molar ratio of monosaccharide compositions in ALF1 was described as follows:Man:Glc:Fuc:Gal:Glc A:Ara=1.00:0.65:0.39:0.47:0.29:0.01.However,in ALF2,the molar ratio was Glc:Man:Rha:Gal=1.00:0.40:0.34:0.54.Linkage and NMR data comprehensively showed that ALF1 mainly contained six kinds of linkage type units as(A)?4)-?-D-Manp-(1?;(B)?3)-?-L-Fucp-(1?;(C)?-L-Araf-(1?;(D)?6)-?-D-Galp-(1?;(E)?4)-?-D-Glc Ap-(1?;(F)?3)-?-D-Glcp-(1?.Both of the fractions had good performance in the in vitro antioxidant activities.The highest DPPH radicals scavenging rates of ALF1 and ALF2 were 76.37±3.02 and 74.71±2.37%at5.0 mg/m L,respectively.ALF1 was proven to be able to inhibit tumor cells without affecting normal cells.Besides,ALF1 were able to protect PC12 cells against H₂O₂-induced oxidative stress.3.The reliable quantification methods of ergothioneine in F.luteovirens fruiting bodies,mycelia and fermentation broth were established.The results show that the content of ergothioneine reached 5.36 mg/g d.w.in F.luteovirens fruiting bodies.Supplementation of amino acids enhanced the ergothioneine accumulation in the F.luteovirens fermentation broth from 0.75 mg/L to 3.97 mg/L.Heterologous expression of flegt1and flegt2 from F.luteovirens genome was performed for biosynthesizing ergothioneine and obtained a small amount of ergothioneine.4.We present a 27 Mb genome of F.luteovirens with 7068 predicted gene models.The genome component and gene functions were predicted.Bioinformatics analysis reveals that genes associated with metabolism of terpenoids and polyketides accounted for the largest proportion.And the genes of glycoside hydrolase were highly enriched in the genome.Predictive analysis showed the biosynthetic gene clusters(BGCs)of Melleolides and provide medicinal activity research basis of F.luteovirens.The results of NR,phylogenetic tree and the genomic synteny analysis confirmed that F.luteovirens belongs to the genus of Floccularia instead of Armillaria as it used to.5.We performed comparative transcriptomic analysis with F.luteovirens samples of four stages for the first time.The most pronounced change in gene expression occurred during the vegetative-to-reproductive transition,and the differentially expressed genes of this period were analyzed.