Study On Antibacterial Effect And Mechanism Of Eupatorium Adenophorum Spreng Extract Against Bacteria

In this study,70% ethanol extract of Eupatorium adenophorum Spreng was evaporated into paste. The paste was extracted with petroleum ether, ethyl ether, ethyl acetate, chloroform, butanol and acetone in accordance with the different polarity, meanwhile active substances of different polarity paste were obtained. Then, the antibacterial tests of organic solvent extracts were conducted against 5 experimented strains. Finally, the most sensitive strain and the best antibacterial extracts were selected. The experiment showed that chloroform extracts exhibited the best inhibitory effect against Rastonia solanacearum, and then the antimicrobial tests were carried out. The mechanisms of inhibition on Rastonia solanacearum by use of chloroform extracts was also explored in some aspects such as physiology, biochemistry and cell morphology.1.70% ethanol extracts of Eupatorium adenophorum Spreng had obviously antimicrobial activities, especially to Rastonia solanacearum with a MIC of 0.0625g/ml, and they also exerted the same function on the other 4 bacteria(Staphylococcus aureus, Bacillus subtilis, Bacillus thuringiensis, Escherichia coli)with 0.25g/ml. Moreover, the extracts of Eupatorium adenophorum Spreng were hot stability, antimicrobial activities were better at pH9;2. The petroleum extracts and acetone extracts had no inhibitory effect on all the experimented strains. The chloroform extracts had more distinctly antibacterial activities against Rastonia solanacearum.3. Zn2+,Mn2+ were added into chloroform extract and Zn2+ were added into ethyl ether, which can increase inhibitory effect remarkly. Other treatments didn't show the similar trend. With the increase of the concentration of NaCl and sucrose, the inhibitory effect gradually improved.4.Inhibitory mechanisms:The result of SDS-PAGE indicated that chloroform extracts completely destroyed or inhibited small moleculars of Rastonia solanacearum while large moleculars also affected to some extent. Observation under transmission electron microscope revealed that the structure of experimented microbes was disrupted by chloroform extracts, experimented microbes' morphology changed as well; chloroform extracts exhibited inhibitory effect against POD,CAT,SDH of Rastonia solanacearum. With the concentration of extract increasing, inhibition effect rose simultaneously. In conclusion, extracts from Eupatorium adenophorum Spreng disordered normal celluar metabolic process, leading to development and reproducibility ceased, ultimately the antimicrobial purpose was achieved. These researches will provide some guidence for the application of controlling Rastonia solanacearum.