Studies On Secondary Metabolites And Bacteriostatic Activity Of Endophytic Fungi From Ligularia Virgaurea

The endophytic fungus is a kind of microorganism resource which has enormous potential. Endophytic fungus is to find a large number of new active substances from traditional medicinal plants and special environmental plants. It will play a significant role in increasing production, biological control, and other areas of the application in the future.The topics in this paper mainly focused on Ligularia virgaurea, the endophytic fungi was isolated, purified and preliminary identified. The antibacterial activity and the influence of Heat, PH, ultraviolet light of endophytic fungi fermentation liquor were tested with Escherichia coli, Salmonella and Staphylococcus aureus. And the bacteriostatic activity strains for the study was molecular identified and culture conditions of the fungi have been experimented. The main results are as follows:1. Separation through tissue, using PDA, MEA, CZAPEK’S 3 kind of isolation medium, were isolated and purified Ligularia virgaurea endophytic fungi 67 strains. From the distribution point of view, the separation of up to 36 strainsstems, leaves were obtained 19 strains and 12 strains. Through the methed of identification of classical morphological, they belong to 5 orders,5 families and 9 generas, and Trichoderma and Fusarium are dominant bacterias.2. Screening of 18 representative of fermentation products’antifungal activity were found,14 strains of this with antimicrobial activity (inhibition zone>8mm) through at least one of the tested bacteria, accounting for 77.78% of the total. Among them,27.78% have good antibacterial activity against E.coli (inhibition zone>12mm), 16.67% with good antibacterial activity against Salmonella,44.44% has good antibacterial activity of S.aureus. According to the best morphological and molecular identification the antibacterial activity of strain N2, which belonged to deuteromycota, Trichosporon orders, Moniliaceae, Trichoderma, Trichoderma asperellum, and eventually named Trichoderma asperellum LB-N2(Accession No:KM207842).3. The stability of fermentation broth of Ligularia virgaurea endophytic fungi N2 results showed:antibacterial activity components of thermal stability was generally, below 60℃ has good stability, the stability in the neutral weak acid environment was best, ultraviolet light effect on fermentation liquor was lesser, fermented liquid activity was consistent under different time of ultraviolet light.4. On the choice of carbon source and nitrogen source, small molecule carbon source and organic nitrogen source had the highest utilization rate and it had the fastest growth Grow in the medium inendophytic fungi of ligularia virgaurea N2.5. Extracting endophytic fungi of ligularia virgaurea N2 fermented liquid with petroleum ether, ethyl acetate, n-butanol three different polarity extractant. The extract activity results showed that N2 broth different extraction bacteriostatic activity relative indication of the size of the difference was significant. The strongest antimicrobial activity was ethyl acetate extraction, petroleum ether extraction phase without doantimicrobial activity, conculusion that the active substance was a strong polar substances, mainly concentrated in ethyl acetate.6. Fermentation liquor of N2 strain was extracted to crude extract, and two highly active components were obtained from the acetyl acetate extract of N2 by silica gel column chromatography. The two compounds were preliminarily elucidated by silica gel column chromatography as:alkaloids and terpenoid substances.