The Studys On Endophytic Fungi Strains With Antibacterial Activity In Lilium Corm

Endophytic fungi refers to those fungus grow in tissues and organs of healthy plants internal in certain stage, or all stages of their life. The effect of the secondary metabolites of endophytic fungi on pests and diseases biological control of the pharmaceutical industry is gradually increasing, because of its species richness, a huge number, but also has a close ecological relationship between other organisms, making it the active substance a rich source of which is a widespread concern, and become one of the hotspots. In recent years, many studies show that the lily extract to a certain extent, the inhibitory effect of both bacteria and fungi. The possibility of endophytic fungi and host plants have a complex relationship, with antibacterial activity of endophytic fungi isolated from lily.Endophytic fungi in Lilium corm were isolated, screened and identified in this paper. One-factor-at-a-time approach was used to screen the suitable growth conditions and medium composition for BH-3, including the suitable fermentation temperature, original pH, inoculation volume, broth volume, basal medium and carbon and nitrogen sources, with the inhibition zones against Staphylocous aureus and Escherichia coli and mycelium weight as responses. Orthogonal experimental design was applied to study the effect of various medium components identified earlier by one-factor-at-a-time approach on the responses, indicating that peptone and KH2PO4showed significant effects on the antibacterial activity by Orthogonal experimental design. Characteristics of the antibacterialactivity against Escherichia coli of the fermentation broth were evaluated by the treatment of different pH, temperature, protease,(NH4)2SO4, ethanol, cyclopeptide qualitative assay, superfiltration and ultraviolet radiation. With (NH4)2S04fractional precipitation, Sephadex G100molecular filtration chromatography and DEAE Sephadex A-50ion exchange chromatography followed by tracks of fraction antagonistic assay.The results show:1. Endophytic fungi were obtained from fresh Lilium corm. Antibacterialactivities of the culture broth were investigated against7strains of pathogens, and strain BH-3showed significant antibacterialactivity.2.0n the basis of the sequence of internal transcribed spacers, it can be determined to be Fusarium oxysporum.3.The optimum concentrations of peptone and KH2PO4were determined by a central composite design. The optimum medium compositions for the antibacterial activity was found to be15g/L glucose,1g/L (NH4)2SO4,6g/L peptone,1g/L yeast extract,0.6g/L MgSO4,0.8g/L KH2PO4, and0.3g/L VB10.03g/L4. An antagonistic protein with antibacterialactivity was isolated and purified.The purified protein was demonstrated to be have weight with55KD by SDS-PAGE.