| Endophytic fungi isolated from the medicinal plants could products the same orsimilar active medicinal compound with the host plant. In recent years, they havebecome the important microorganism source for the screening of new, highly efficient,broad-spectrum, antimicrobial active compound. In this study, one of the25strainsnamed PG23was carried out various aspects researched, which produces highlyefficient, broad-spectrum antimicrobial activity compound to restrain pathogens.Morphology combined with ITS-5.8s rDNA sequence analysis showed that theendophytic fungi PG23was classified as Ascomycota Leculoascomycetes DothidealesDothideales phoma sacc. The biochemical characteristic of endophytic fungi in theresearch shows that it has the ability to use nitrate and produce curd enzyme.The Escherichia coli.and Staphylococcus aureu used as indicator bacteria,theendophytic fungi PG23fermentation medium was optimized in order to improve theproducing antibacterial compound ability. The respective composition of optimizedfermentation medium were as follow: Potato juice as the basis liquid; glucose(w/v)2.5%, Soybean Oil(w/v)0.5%, maize meal (w/v)0.15%,taraxacum juice(v/v)8%;Potato juice as the basis liquid, glucose(w/v)2.6%,soybean oil(w/v)0.53%,maizemeal0.10%(w/v), taraxacum juice(v/v)7.06%.The endophyte of Taraxacum was cultured in the optimized liquid fermentationmedium, the inhibition zone diameter of Escherichia coli reached26.7mm which wasincreased about22.47%compared with primary medium and the inhibition zonediameter to Staphylococcus aureu reached40.0mm which was increased about77.8%compared with primary medium. According to the optimal medium,the optimumculture conditions are initial PH value6.5, liquid volume45mL/250mLflasks, inoculum10%, culture temperature26℃,rotating rate160r/min.The property of antibacterial active compound producing by taraxacum endophytePG23was researched.1. The antibacterial active substances display good thermalstability rangeing from30℃to100℃;2. The compound has good bactericidalcapacities against G-E.coli in pH1~7,and it has good bactericidal active against G+Staphylococcus aureus in pH1~11,at the same time, it has high inhibitory activity against Aeromonas hydrophila and Edwardsiella pathogenic microorganisms in fish;3.The active compound producing by taraxacum endophyte PG23could eliminateβ-lactamase resistance in Escherichia coli;4. The ingredient of the active compoundproducing by PG23were identificated by chemical method. The main active compoundcontains phenols, recuding sugars and organic acid.5. The characterization offermenting liquor which contains antibacterial active compound had analyzed bycontinuous extracting method. the antibacterial active compound main remain in ethylacetate phase, n-butyl alcohol phase and raffinate phase of n-butyl alcohol.6. Theantibacterial active compound in the ethyl acetate phase was separated by TLC andSilica gel column chromatography. the separation of active substance was crystallize insolutions.7. the coarse crystalline was separated and anlysised by GC/MS. The coarsecrystalline mainly contain three compound:3-methyl phenol Adjacent methyl salicylicacid methyl ester and2-H,3-methyl,3-methyl benzothiophene.8. Compared totaraxacum juice extracted by ethyl acetate, the main compound do not find the similarpolar compound, which was extracted by ethyl acetate from the PG23fermentationbroth.The antibacterial metabolite was produced by taraxacum endophyte PG23,which hasgood heat-resistant, good acid and alkali resistance broad-spectrum, antimicrobial activeproperties. At present, three antibacterial compound was isolated from PG23. They are3-methyl phenol Adjacent methyl salicylic acid methyl ester and2-H,3-methyl,3-methyl benzothiophene. |
