Identification And The Secondary Metabolites Research Of The Fungal Endophytes In Locoweed

In order to ascertain the species, distribution and genetic development of the endophyticfungus from the major locoweed in the west meadow of China and the development prospectsof their secondary metabolites which own antibacterial activity, the study collected Oxytropisflabra, Oxytropis Ochrocephala Bunge, Oxytropis Kansuensis, Oxytropis Deflexa, OxytropisCoerulea and Astragalus variabilis samples to isolate and purify the endophytic fungi in thedifferent tissues (root, stem, leave, flower and seed), then used the morphology techniquesand ITS sequence analysis to identify their species, and built the phylogenetic tree byNeighbor-Joining method to analysis their genetic relationship. Staphylococcus aureus,Bacillus subtilis, Escherichia coli and Salmonella were selected as indicators to make theantibacterial tests of the fungi secondary metabolites by paper disc diffusion method. At last,use the target strain to ferment lardely sacle, then separate and purify the chemicalcomposition of the target strain secondary metabolites. The achieved results were as follow:1.265fungal colonies were isolated from the collected locoweed, which were combinedto38kinds of different endophytic fungus. The distribution of the endophytic fungus in thetissues of locoweed was different. Fusarium sp., Alternaria sp. and Paecilomyces sp. were thedominant strains of the locoweed samples, which occupied16.98%,11.33%and9.81%of thetotal isolated colonies respectively. Phylogenetic analysis showed that38kinds of endophyticfungus could be divided into two populations based on the evolutionary kinship. Theendophyte species and the distance of genetic relationship belonged to locoweed species,tissues, ecological environment and other factors.2. The antibacterial tests results showed that the secondary metabolites of29strains atleast (76.32%of the total strains isolated) presented the antibacterial activity against one ofthe tested bacteria, of which27strains presented the antibacterial activity againstStaphylococcus aureus,20strains presented the antibacterial activity against Bacillus subtilis,20strains presented the antibacterial activity against Escherichia coli, and9strains presentedthe antibacterial activity against Salmonella. And the secondary metabolites antibacterialactivity of XJ-JJ-1, XJ-JJ-2, XJ-JJ-5, XJ-ZJ-2, GJ-JQ-2, GBQ-3and GGJ-Y-1were obviously.Above all, the XJ-JJ-2and XJ-ZJ-2were found to have stronger antibacterial activity against the four tested bacteria.3. The GC-MS analysis showed that there were36and42compounds in the fermentationbroth and mucelium respectively, the same compounds of them were11, the organic acidswere the main activity ingredients. And the compounds whose relative content was greaterthan1%were both10in the fermentation broth and mucelium, but the main composition ofthe fermentation broth and mucelium were not all the same. There were two unknowncompounds in the mycelium of XJ-JJ-2, and their relative content were15.474%and8.424%.Two compounds were obtained from the extract of XJ-JJ-2, which need further antibacterialactivity research, physical properties and chemical spectroscopic characteristics analysis.