A new bacteriocinogenic activity: megacin BII encoded by plasmid pSE 203 in strains of Bacillus megaterium

Mesophilic strains producing a new bacteriocin: Megacin BII, have been isolated from strains of Bacillus megaterium. Facultatively thermophilic strains producing Megacin BI were less sensitive to this new activity than non-producing mesophiles and strains producing Megacin BII were also more resistant to Megacin BI. Strains producing Megacin BII contained a large plasmid of 36.10(6):pSE 203. This plasmid was introduced into non-megacinogenic acceptor strains by protoplast transformation, they then became megacin producers and immune to Megacin BII. Plasmid pSE 203 has been mapped with endonucleases. No similarity to the Megacin A plasmids pBM 309 [Rostás et al. (1980) and pBM 113 (von Tersch and Carlton (1983 b)] was evident.