Study On The Antibacterial Activity Of The Metaboiities In Actinomycetes BZ45

Maize is the world and China’s major food, fodder, and industrial crop. However,the yield loss is more than50%on a regular basis due to the hazards of the northerncorn leaf blight (NCLB) caused by Setosphaeria turcica, which occurs frequently inmaize growing areas. Currently, NCLB is mainly controlled by resistant cultivarsagainst S. turcica, while cultivation management and chemical control are thecomplement. However, chemicals control effect is not stable, and easy to pollute theenvironment, so the development of new biocontrol agents is one of the mostimportant method to control NCLB.In this study, the fermentation product of Actinomycetes BZ45was screened andextracted into the petroleum ether layer, the ethyl acetate layer, the aqueous layer andthe N-butanol layer. Applying the filter paper diffusion method and inhibition ofmycelial growth rate method to analysis the antibacterial activity of the abovecomponents, bacterial and plant pathogens including S. turcica used as target strains.The experiment results shows that the petroleum ether layer extract had significantinhibitory activity to Escherichia coli; the N-butanol layer extracts has significantinhibitory activity to S. turcica. Then the petroleum ether layer and the N-butanollayer extract was screened by bioassay-guided fractionation bioactivity to investigateantimicrobial components, according to the GC-MS analysis results, the petroleumether layer contains29kinds of compounds and the N-butanol layer extract containscompound A, which had significant fungistasis activity to S. turcica.Filter paper diffusion method was used to analyse the antibacterial activity of thepetroleum ether layer extract in vitro, the results shows that, at the concentration of50mgml-1of petroleum ether layer extract, the inhibition diameter of E. coli was13.28±0.52mm, the inhibitory rate was47.72%. While in the vitro fungistasis activity study of compound A from the N-butanol layer extract, the inhabitation of mycelialgrowth rate shows at the concentration of50mgml-1of compound A, the antibacterialdiameter of S. turcica was15.33±0.61mm, and the inhibitory rate was54.94%.The fungistasis activity of compound A from the N-butanol layer extract in vivowas analysed in maize. Relative lesion areas were compared between plants treatedwith compound A or with water after inoculation test with S. turcica spores. Withpretreatment of compound A, the maize Leaves infestation area was28.12±3.35mm2,while with water treatment, the maize Leaves infestation area was as much as182.78±17.12mm2, the above result indicates that active ingredient A from N-butanollayer of Actinomycetes BZ45have significant fungistasis activity on S. turcica.The antimicrobial activity stability research of the petroleum ether layer extractand the ingredient A from N-butanol layer of Actinomycetes BZ45were performed.High temperature and ultraviolet irradiation treatment can not change theantimicrobial activity of the petroleum ether layer extract and the ingredient A fromN-butanol layer, which was verified in antimicrobial activity analysis in E. coli and S.turcica.