Purification Of Antagonistic Protein Of Acremonium Persicinum And Its Preliminary Application

The control of plant disease mainly includes chemical control and biocontrol,although chemical fungicides have the advantages of wide application and high efficiency,but bring environmental problems at the same time.Nowadays,food safety problem has attracted widespread attention,biocontrol is becoming a hot research topic.Acremonium persicinum(has been patented)is a novel strain which was isolated from soil had been shown to be antagonist against many plant diseases.The early experiment has proved the antimicrobial substance secreting from the strain was protein.Fusariun solani and Bipolaris carbonum has been chosen as the tested pathogens.The antibacterial protein of A.persicinum was isolated,the preliminary antibacterial mechanism and application of it were studied,in order to provide the theoretical basis and technical support on the strain`s better utilization.The antagonistic protein of A.persicinum strain fermentation was extracted by ammonium sulfate precipitation,chromatographied by Sephadex G-75,purity detected by SDS-PAGE and mass spectrometry analysis,the purified antibacterial substance was demonstrated to be a protein which molecular weight was 15 k Da.The research of antagonistic protein stability showed: it was insensitive to temperature.It was still maintain its high inhibitory activity when the crude protein was processed at 121℃after30 minutes;it was sensitive to pH,the protein had no antibacterial activity in strong acid or alkali conditions,antibacterial protein had the strongest inhibitory activity at pH6.0.The spores and mycelia of F.solani were treated by this protein,then observied by microscope,the spores germ tube were getting passivation and couldnot growth as the treatment time prolonged,under the protein concentration of 90%,spore germination rate was only 15.6%;the detection of mycelia and antioxidant enzymes showed: the electrical conductivity increased,three kinds of antioxidant enzymes changing trend of mycelia were consistent in 96h: first increased and then decreased,three kinds of antioxidant enzymes reached the highest activity at 24 h,fell to the lowest at 96 h.The study results showed that the cell membrane permeability of mycelia changed by the treatetment of antibacterial protein,which resulted in cell content leakage and death.The soybean has been chosen as the research materia,through a pot experiment to determine the content of three kinds of antioxidant enzymes,exploring the application prospect of the crude protein of A.persicinum.The results showed that: comparing with the normal soil,the POD and CAT activity of soybean leaves or roots of the soil adding A.persicinum crude protein or carbendazim was not increased,but SOD activity was improved.Compared with the normal soil,the content of three kinds of antioxidant enzymes in soybean leaves inoculated with Sclerotinia sclerotiorum of the soybean treated by applying crude protein in soil were deterimined,SOD activity could be enhanced in soybean leaves,but POD and CAT activity was not increased.This result was consistent with the change of root and leaf after soil treatment.