Antimicrobial Activity And Steroid Analysis Of The Endophytic Fungi From Paris Polyphylla Var. Yunnanensis

Endophytic fungi are defined as the fungi which spend the whole or part of their lifecycle colonizing inter-and/or intra-cellularly inside the healthy tissues of the host plant, typically causing no apparent symptoms of disease (Tan et al. 2001). Up to now, large amounts of endophytic fungi have been isolated from hundreds of plants, some of which have been detected to produce bioactive substances that would be involved in relations between endophytes and their host plants. Some secondary metabolites produced by the endophytes have been tested to have their applications as medicinal and agrochemical candidates(Strobel 2003). In this thesis, endophytic fungi were separated from the rhizomes of P. polyphylla var. yunnanensis, and identified by morphological and molecular methods. The steroidal components of the endophytic fungi were analyzed, and antimicrobial activities of the extracts were screened.1,About sixty-three fungal endophytic isolates were separated from the rhizomes of Paris polyphylla var. yunnanensis. The isolates were characterized and grouped based on the culture characteristics and the morphology of colony growth and conidia. 16 representative ones were selected for further study. Of them, the most frequent genus was Fusarium oxysporum (i.e. Ppf5, Ppf11, Ppf14, Ppf15 and Ppf16). The other isolates were identified as Fusarium redolens (Ppf1), Gliocladiopsis irregularis (Ppf2), Fusarium sp.(Ppf3) Plectosphaerella cucumerina (Ppf4), Padospora sp. (Ppf6), Gliomastix murorum var. murorum(Ppf7), Aspergillus fumigatus(Ppf9), Pichia guilliermondii (Ppf10), Neonectria radicicola (anamorph: Cylindrocarpon) (Ppf12) and one uncultured mycorrhizal ascomycete (Ppf13) separately based on their morphological and molecular features.2,15 representive isolates were screened for their antimicrobial activity. Of them, isolates Ppf1, Ppf3, Ppf7, Ppf8, Ppf9 and Ppf14 showed stronger antibacterial activity in their n-butanol extracts than other ones. Isolates Ppf1, Ppf15, and Ppf16 showed stronger antibacterial activity to Candida albicans in their filtrates n-butanol extracts. By the TLC-bioautography method assay, the isolates Ppf1, Ppf3, Ppf7, Ppf8, Ppf9 and Ppf10 showed stronger antimicrobial activity to Magnaporthe grisea in their n-butanol extracts. 3. Fungal isolates Ppf2, Ppf6, Ppf7, Ppf11 and Ppf16 were found to produce more steroids with their higher yield in suspension culture by comparing to other isolates using Liebermann-Burchard visualization. Thin layer chromatography showed that fungal isolate Ppf11 were detected to possibly have diosgenin in Petroleum ether extracts of their suspension cultures.This thesis would benefit for future separation of the endophytic fungi from P. polyphylla var. yunnanensis rhizomes, for steroid compound study of the endophytic fungi, for antimicrobial compound study, as well as for coevolution study of the endophytic fungi with their host P. polyphylla var. yunnanensis.