Endophytic Fungi Isolation From Medicinal Plants And Study On Active Substances Of Active Strain Isolated From Panax Ginseng

As a big group of microbe inhabiting in the living tissues of plants, endophytic fungi have nosignificantly negative effects on the host plants during their whole life history or some phases. There arereports showed that endophytic fungi can produce the same or similar compound with their host. In thisscientific dissertation, some medicinal plants with antimicrobial activity were selected as the material forisolation of antibacterial endophytic fungi. RP, isolated from Panax ginseng, one of have the strongantibacterial activity endophytic fungus was identified by physiological and biochemical techniques, andthe active substance of the fermentation broth of RP were also studied. The results were as follows:1. By tissue surface-sterilized, 48 strains endophytic fungi were isolated on PDA, CMA, MEA, HMA andTWA from stems, leaves and flowers of 12 kinds of medicinal plants under 20℃in the dark. Of these 48isolates, there were 20 strains were isolated from stems, 19 strains were from leaves and 3 strains werefrom flowers. PDA-streptomycin media was the suitable media for isolation in this research.2. Screening the antibacterial activity of fungus disc, fermentation broth and ethanol extract of mycelia ofall the 48 strains endophytic fungi. There are 4 strains that all the three parts have strong antibacterialactivity isolated from Astragalus membranaceus, Scutellaaria baicalensis, Bupleurum scorzonerifoliumand Panax ginseng. And the strain RP isolated from Panax ginseng had the strongest activity, the fractionalinhibition against Staphylococcus aureus was as high as 76%. RP was elected for the further study.3. The suitable carbon source for isolate RP was rice and suitable nitrogen source was yeast. The optionaltemperature was 24℃and the strain was incubated for 25 days, it showed strong antibacterial activity.Minimal Inhibitory Concentration against Staphylococcus aureus was 8μg/mL. Isolate RP was identified bymorphology method, and it belonged to Phomopsis genus. 5.8S rDNA of isolate RP was sequenced.Sequence length was 539bp, it was 99% homology to the Preussia flanaganii in GenBank nucleotidesequences databases. But they were different from morphological character, further study was needed.4. Preliminary study on the active substance in fermentation broth. Screening the assistance site of activesubstances by macroporous resin trabecular. The results revealed that the active substances were eluted outwhen eluted solution was 80%-90% ethanol. And found there was also saponin in the fermentation brothand through TLC we got 3 spots, the Rf were: Rf1=0.3974, Rf2=0.5128, Rf1=0.8846. And the spot atRf1=0.3974 had the same site with panaxoside Re. So we suspect that there was panaxoside Re in thefermentation broth of RP.