Lactobacillus plantarum BM-1 isolated from a traditionally fermented Chinese meat product was found to produce a novel bacteriocin that is active against a wide range of gram-positive and gram-negative bacteria. Production of the bacteriocin BM-1 started early in the exponential phase and its maximum activity (5120 AU/mL) was recorded early during the stationary phase (16 hr). Bacteriocin BM-1 is sensitive to proteolytic enzymes but stable in the pH range of 2.0-10.0 and heat-resistant (15 min at 121°C). This bacteriocin was purified through pH-mediated cell adsorption-desorption and cation-exchange chromatography on an SP Sepharose Fast Flow column. The molecular weight of the purified bacteriocin BM-1 was determined to be 4638.142 Da by electrospray ionization Fourier transform mass spectrometry. Furthermore, the N-terminal amino acid sequence was obtained through automated Edman degradation and found to comprise the following 15 amino acid residues: H2 N-Lys-Tyr-Tyr-Gly-Asn-Gly-Val-Tyr-Val-Gly-Lys-His-Ser-Cys-Ser. Comparison of this sequence with that of other bacteriocins revealed that bacteriocin BM-1 contains the consensus YGNGV amino acid motif near the N-terminus. Based on its physicochemical characteristics, molecular weight, and N-terminal amino acid sequence, plantaricin BM-1 is a novel class IIa bacteriocin.
Keywords: Bacteriocin; Lactobacillus plantarum; N-terminal amino acid sequence.
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