Research On Diversity And Metabolite Activity Of Plant Endophytic Fungi

Endophytes are those bacteria or fungi which live inside the organ and tissue of healthy plants during some or all stages of their life. Its endogeny can be proved through histological method, or isolation from strongly surface disinfected tissue, or direct amplification of microbe DNA from plant tissue.The biological diversity of plants and fungi determines the biodiversity of plant endophytic fungi. Over the past decade, researchers have isolated more than 170 genus of endophytic fungi including ascomycetes, basidiomycetes, zygomycetes, chytrid and semi-known microorganisms from hundreds of plants. With the expansion and in-depth of research on plants and fungi, there will be a large number of unknown valuable resources of endophytic fungi to be explored and researched.It has been found that many endophytic fungi produced the same or similar biological active substances with their host plant, based on their symbiotic relationship. That provides a good basis for screening and exploring of bioactive substances of endophytic fungi.Endophytic fungi have a variety of species, abundant novel metabolites, natural low toxicity, and various biological activities, such as antimicrobial, antitumor, antiviral, insecticidal, immune regulation, degradation of environmental waste and plant growth promotion. The biological active substances produced by plant endophytic fungi have played an important role in many aspects, such as drug development, environment waste degradation, energy production and agricultural defense.They have solved those problems such as lack of resources, ecological destruction and species extinction caused by extracting product from rare plant resources, and shorten the culture cycle.The purpose of this study is to understand the diversity of plant endophytic fungi, screen endophytic fungi metabolites for the lipid degradation activity and antifungal activity, and isolate and purify active substances.This study selected three provinces in the northeast, northwest and southwest parts of China, collected 43 species of medicinal plants, isolated 16 genus, 332 strains of plant endophytic fungi. There are obvious differences of these endophytic fungi distribution in different regions and different host plants, there are also some differences in different plant tissues, showing a rich biodiversity. In the screening of the lipid degradation activity, 86 strains were screened from the isolated 130 strains of endophytic fungi, indicating that lipase is ubiquitous in fungi. The lipid degradation activity of L77 was relatively high, isolated from Yunnan Dendrobium, identified to be Aspergillus flavus through morphological and molecular biology methods. At present, the fungi screened for lipid degradation activity are almost from soil and hot spring, rarely from plants. Dendrobium is one of the top grade Chinese herbal medicines recorded earlist in ancient documents in China, which has many functions such as clearing away heat and toxicant, clearing liver and improving vision, regulating blood lipid, reducing blood sugar and antitumor. Aspergillus is a genus of fungi with rich biological activity. This Yunnan Dendrobium endophyte Aspergillus flavus, has good research value, in the future, this study will continue to optimize its fermentation conditions, isolate and purify its lipase, improve it by gene engineering, and explore other bioactivities.In the screening of the antifungal activity, 13 strains were screened from 54 strains of isolated endophytic fungi fermentation liquid. Among them, L43 has broader antifungal spectrum and high antifungal activity to Candida albicans,Aspergillus fumigatus,Fusarium solani and Trichophyton rubrum. The strain was isolated from Jilin Ginkgo biloba, identified to be Penicillium brevicompactum through morphological and molecular biology methods. Ginkgo biloba is a precious medicinal resources, as one of the oldest medicinal plants known as living fossil, it has many medicinal values such as antibiosis, removal of cough and diseases.This study established the isolation and purification system of antifungal activity substance, and obtained antifungal activity components of the Penicillium brevicompactum fermentation liquid, by silica gel column chromatography, TLC, HPLC and mass spectrometry. This study will continue to isolate the monomer on that basis, in order to provide the theoretical basis and technical support for research on high efficient, low toxic and natural antifungal agents.