The purification and properties of megacin, a bacteriocin from Bacillus megaterium

Abstract

Megacin formation was induced by ultraviolet irradiation of a growing culture of Bacillus megaterium 216. The culture undergoes mass lysis 90 min. after irradiation, and megacin is released into the medium. A method for the production of large volumes of megacin-containing lysate has been devised. Megacin was isolated from the lysate by isoelectric precipitation, ammonium sulfate fractionation and chromatography on diethylaminoethylcellulose. The purified preparation was homogeneous by electrophoresis and ultracentrifuging. From sedimentation-velocity experiments a value of 51,000 was obtained for the molecular weight Megacin appears to be a simple protein. It is denatured by heat and by 7[image]-urea but is resistant to attack by pepsin, trypsin and chymotrypsin. Megacin is a potent antibacterial agent and is capable of inhibiting the growth of sensitive cells at a concentration of 10 [mu]mg/ml or 136 molecules of megacin/treated cell.