Study On Diversity And Bioactive Products Of Endophytic Fungi

Endophytic fungi are fungi that colonize the inside of healthy plant tissues, persisting for a certain amount of time without causing visible disease symptoms. Some endophytic fungi can produce bioactive metabolites, similar to their host, and become a novel source of potentially useful medicinal compounds. Endophytic fungi, which vastly exist in nature, have been a research focus in recent years and they become new sources of microorganisms.In this paper, endophytic fungi from medicinal plants were studied for their diversity and bioactive products. This paper comprises three parts of research work.First, 1,142 strains of endophytic fungi were isolated from 89 kinds of medicinal plants sampled from Tiasnmushan Natural Reserve and Qingliangfeng Natural Reserve in Zhejiang Province, and analysis of endophytic fungi in different plants and different organs has been done.Second, 52 Fusarium strains isolated from Taxus mairei, Torreya grandis and Cephalotaxus fortunei have been identified with molecular biological methods. The distribution of Fusarium species has been analyzed in these three plants as well. The results showed that these Fusarium strains were members of nine known Fusarium species/clades and five putative new Fusarium species/clades: F. 'Lateritium Clade IIC', F. sp. A, F. sp. B, F. sp. C and F. sp. D. The species and amount of the strains isolated from these three plants were different distinctively. A part of these strains were cultured with MID liquid medium for studying their secondary metabolites. As a preliminary result, three strains of F0021, F0042 and F0081 can produce taxol, a valuable antitumor medicine.Third, three endophytic Trichoderma spp. of F0869, F0870 and F0986 which produce a new antibiotic, trichodermisin, were identified to be a new Trichoderma species, Trichoderma taxii sp. nov. One special sequence of this species has been found by applying RAPD method. Bioassays have been done to trichodermisin, the results showed it strongly inhibited Rhizoctonia solani and Botrytis cinerea, and its antibiotic activity to Botrytis cinerea was higher than amphotericin B.