Isolation,Identification Of Endophytic Fungi From Conyza Blinii H.Lév And Study On The Antioxidant Capacity Of Strains Producing Flavonoid

Conyza blinii H.Lév is the biennial herbs of genus Chrysanthemum,as a genuine Chinese herbal medicine in Sichuan,its medicinal development is limited by the lack of germplasm resources.As a kind of fungi living in healthy plant tissues,endophyte has become an important microbial resource.From the perspective of endophytic fungi,we can better solve the problem of resource shortage,and select endophytic fungi with certain biological activity,which provides a new idea for the development of resources of Conyza blinii H.Lév.In the study,21 endophytes were isolated from the wild Conyza blinii H.Lév by tissue isolation method,12 of them were isolated from leaves and 9 from stems.Ten genus were identified by morphology and molecular biology,which the dominant genus were Chaetomium sp.and Colletotrichum sp..Seven strains of endophytic fungi,L1,L1-1,L4-1,L7,L9,L11,L12 and L12-2,were screened by the color reaction of flavonoids,and the content of total flavonoids in mycelia was determined.The results showed that the content of total flavonoids in L11 mycelium was the highest,which could reach 19.7 mg/g.Esherichia coli,Staphylococcus aureus,Pseudomonas aeruginosa and Bacillus subtilis,the four common gram-negative and gram-positive bacteria,were selected for the antibacterial experiment of endophytic fungus and its fermentation liquid.The results showed that the seven strains producing flavonoids had no antimicrobial ability to the four tested strains,and their fermentation liquid had four kinds of antimicrobial ability,which were the fermentation liquid of strains L1-1,L9,L11 and L12-2.L9 fermentation liquid had the strongest antimicrobial ability,and the inhibition effect on the four strains was Esherichia coli > Bacillus subtilis > Staphylococcus aureus >Pseudomonas aeruginosa.In vitro antioxidant activity of flavonoids producing endophytic fungi and the antioxidant properties of Caenorhabditis elegans in vivo were studied,and their antioxidant activities were preliminarily analyzed.The results showed that the scavenging rate of L11 to DPPH radical was up to 87.1%,L12-2 to hydroxyl radical was up to 83.9%,L1-1 to superoxide anion radical was up to 36.9%,7 strains had significant scavenging effect on DPPH free radical and hydroxyl free radical,but weaker scavenging effect on superoxide anion free radical.The results showed that the activities of SOD,CAT and GSH-Px in the treated C.elegans were significantly higher than those in the control.The strongest SOD activity was L1-1,which is 32.89 U/ml,77.80% higher than the control,the strongest CAT activity was L12,which is 6.91 U/ml,78.58% higher than the control,and the strongest GSH-Px activity was L12,which is 46.59 active units,85.83% higher than the control.The results of this study can promote the effective utilization of endophytic fungi of Conyza blinii H.Lév,and provide a theoretical basis for the development and utilization of the function of Conyza blinii H.Lév from microbial resources.