Abstract:

In order to provide a theoretical basis for the application of the antibacterial protein, the antibacterial protein was isolated from fermentation broth using ammonium sulfate fractionation and the antibacterial activity on plant pathogenic fungi and bacterium were investigated by the method of inhibition zone. The result indicated that the crude extracted protein produced by the stain XZG-11 had the strongest antibacterial activity to Pseudomonas solanacearum E. F. Smith. It also showed strong inhibitory activity against various plant pathogenic fungi, such as Alternari solani, Botrytis cinerea, Fusarium oxysporum f. sp. niveum, Fusarium sp. and Fusarium head blight. The gram-positive bacteria such as Bacillus subtilis, Candidal vaginitis and Staphylo-coccus aureus were strongly inhibited by the antifungal protein. Besides, the antifungal protein also exhibited inhibitory effect on gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa. This antifungal protein was relatively stable between pH5.0 and pH11.0 and below 80℃. It was resistant to RNase but was sensitive to protease K and trypsinase. The antibacterial protein of Bacillus subtilis XZG-11 had the strong stability and the broad antimicrobial activity to plant pathogenic fungi and bacterium.