Detection and characterization of cerein 7, a new bacteriocin produced by Bacillus cereus with a broad spectrum of activity.

A bacteriocin-producing strain of Bacillus cereus was identified and isolated from a soil sample. The bacteriocin could be purified by a two-step procedure: ammonium sulfate precipitation of culture supernatants followed by a butanol extraction step, the antibiotic was recovered from the organic phase. The peptidic nature of the bacteriocin was proven by its sensitivity to proteolytic enzymes; its molecular mass, determined by mass spectrometry, was 3940 Da; and its amino-terminal sequence (GWGDVL) is unique in the databases. The compound was active against most Gram-positive but not Gram-negative bacteria. This is to our knowledge the first bacteriocin with these characteristics reported to be produced by B. cereus.