Abstract: Burkholderia contaminans B-1, isolated from the surface of apricots, is an antagonistic bacterium against Botrytis cinerea and other important postharvest pathogenic fungi in fruits and vegetables. In order to investigate the mechanism of action of B-1, we extracted a protein with antimicrobial activity after lysis of the cells. The protein was purified by bioassay-guided fractionation using fractional ammonium sulfate precipitation, DEAE-cellulose DE-52 ion-exchange and Sephadex G-100 gel filtration column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis suggested that the purified protein was homogeneous and its apparent molecular mass was 17.6 kDa. The protein was stable to heating and pH variations and was insensitive to organic reagents, protease and UV irradiation. Its inhibitory activity was increased by 12.5% in the presence 50 mg/mL Tween-80 as compare to that of the control (CK). The protein was sensitive to SDS and dithiothreitol (DTT).

Key words: Burkholderia contaminans, antifungal protein, isolation and purification, characteristics