Activity Screening Of Endophytic Fungi And Metabolites Of SIPI3.0550

Endophyte,which can produce various bioactive substances,including insecticidal,antimicrobial and antitumor compounds etc.,are special and important microorganisms with taxonomic diversity. The endophytic fungi preserved in our laboratory were cultured with solid-state fermentation and the mycelium were extracted with 1.5 times of organic solvent (v/v). Nearly 8,000 samples of the fermentation extracts were preserved. Their antibacterial activity (G+ bacteria such as Bacillus subtilis,Staphylococcus aureus,Sarcina lutea,G- bacteria such as E. coli,fungi such as Candida albican and resistant bacteria such as Pseudomonas aeruginosa,MRSA,Acinetobacter baumannii) were examined. A 45% antibiotic-producing strains was found. The strain SIPI3.0550 with highest antibacterial activity was selected for further research. According to its growth state of colony,morphology of mycelium,spores and partial sequences of 18S rDNA,SIPI3.0550 was identified as Aspergillus fumigatus.The extract efficiency of mycelium were also examined by different organic solvents,and acetone was considered as the most suitable. A test of the fermentation periods was accomplished and found the optimal fermentation time was 30 days. The stability of fermentation products of SIPI3.0550 (monomethylsulochrin,trypacidin and C19H19O8) were also studied in different temperature,pH and light intensity.Biological assay,TLC and HPLC were used to detect the separation and purification of SIPI3.0550 metabolites. Two adsorption resin,NM100 and microspheresⅠ,were selected to separate and purify the metabolites. Three compounds were purified with the purity over 99% (HPLC). The structures were elucidated through physicochemical properties and spectral analysis (NMR,MS,etc.),two of which were identified as monomethylsulochrin,trypacidin,and the third's molecular formula was C19H19O8. Their antibacterial activity were also examined,and trypacidin was found possessing activity to resistant Staphylococcus aureus,Bacillus subtilis,Sarcina lutea and MRSA. The MIC against Staphylococcus aureus,Bacillus subtilis and Sarcina lutea was 16μg·mL- 1,and the MIC against MRSA was 32μg·mL-1.In our research,a new fermentation,solid-state fermentation,and a new separation material,microsphere resin,were used to achieve higher yeild of fermentation products. Trypacidin possessed the antibacterial activity against sensitive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus,and its activity was not affect byβ-lactamase. It was conclude that trypacidin have a great potential for further research.