Isolation And Purification Of Antimicrobial Protein From Xenorhabdus Spp.BJ

Xenorhabdus and Photorhabdus are harbored as symbionts in the intestine of the infective juvenile stage of nematodes belong to the families Steinernematidae and Heterorhabditidaerespectively, the former reseach suggested that their fermentation product has insecticidal activities, antibacterial, antifungal and antitumor, these specific biological fuction make symbionts bacterium a kind of neotype organism resoure with development potential. In this paper, through research of inhibiting activity against Pytophthora melonis Katsura in nine symbionts bacterium, Xenorhabdus spp. BJ, that isolated from Steinernema carpocapsae by our laboratory , was found to has higher antagonistic activities, then fermentation factors that influence antagonistic activities of Xenorhabdus spp BJ crude proteins and partial property of crude proteins were researched,and different protein with antagonistic activity was isolated and purified from fermentation liquor and bacterium itself. the main results were gained in this study as follows:1. We extracted crude proteins with ammonium sulphate at different saturation from ferment solid of BJ strain and cultured BJ strain under different conditions and studied the antagonistic activities of the crude proteins. The assay showed that crude protein with ammonium sulphate at 60-85% saturation has the biggest antagonistic activities and the strain could serecte lots of antifungal crude protein under 28℃ degree, in TSB medium of pH 7. 2 and cultured 48 hours.2. Crude proteins was extracted from precipitation of the cell culture of BJ strain with ammonium sulphate at 60 ~ 85 % saturation. The determination of bioactivity of this antagonistic protein showed that its inhibitant activity depressed evidently when treated with 100℃ for 30 minutes. All those indicated that the protein could endure high...