Characterization, N-terminal sequencing and classification of cerein MRX1, a novel bacteriocin purified from a newly isolated bacterium: Bacillus cereus MRX1.
OBJECTIVE
To purify and characterize the bacteriocin produced by strain MRX1.


RESULTS
A bacteriocin-producing strain was isolated and identified as Bacillus cereus. The bacteriocin, called cerein MRX1, was purified from the culture supernatant using hydrophobic interaction, cation-exchange chromatography and RP-HPLC. It could also be purified in abundance from the cell surfaces of the producer strain. Mass spectrometry revealed its molecular mass of 3137.93 Da. Sequencing of chemically modified bacteriocin identified its partial sequence: DWTCWSCLVCAACSVELL. Amino acid analysis, confirmed by (1)H-NMR, suggested cerein MRX1 to be a class II bacteriocin. This bacteriocin was remarkably hydrophobic, heat-stable and could withstand a wide range of pH. It exhibited a bactericidal mode of action against Bacillus coagulans JCM 2257(T). Cerein MRX1 was especially active against spoilage bacteria such as Bacillus subtilis and Listeria innocua (MICs in the 1 microg ml(-1) range). In contrast, lactic acid bacteria were resistant or required higher concentrations to be inhibited.


CONCLUSIONS
Cerein MRX1 is similar by its N-terminal sequence to thuricin 17 recently isolated from Bacillus thuringiensis NEB17. However, the two bacteriocins are different by their molecular masses and amino acid compositions.


CONCLUSIONS
Chemical stability of cerein MRX1 and its ability to inhibit a large number of undesirable bacteria may give an advantage to its food or clinical application as an antibacterial agent.
Sebei
S
S
Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan. sebeisamir@yahoo.fr
Zendo
T
T
Boudabous
A
A
Nakayama
J
J
Sonomoto
K
K
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000900:Anti-Bacterial Agents / Q000032:analysis / Q000096:biosynthesis* / Q000494:pharmacology; D001407:Bacillus / Q000187:drug effects; D001409:Bacillus cereus / Q000302:isolation & purification / Q000378:metabolism*; D001430:Bacteriocins / Q000235:genetics / Q000302:isolation & purification* / Q000494:pharmacology; D001431:Bacteriological Techniques; D001483:Base Sequence; D005516:Food Microbiology; D008087:Listeria / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000596:Amino Acids; D000900:Anti-Bacterial Agents; D001430:Bacteriocins; C527588:cerein MRX1, Bacillus cereus