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BioMed Research International
Volume 2016 (2016), Article ID 8521476, 7 pages
Research Article

Isolation and Characterization of a Broad Spectrum Bacteriocin from Bacillus amyloliquefaciens RX7

1Department of Animal Resources Science, Dankook University, Cheonan 31116, Republic of Korea
2National Instrumentation Center for Environmental Management, Seoul National University, Seoul 08826, Republic of Korea

Received 27 December 2015; Revised 31 March 2016; Accepted 17 April 2016

Academic Editor: Moreno Bondi

Copyright © 2016 Kong Boon Lim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We isolated a Bacillus strain, RX7, with inhibitory activity against Listeria monocytogenes from soil and identified it as Bacillus amyloliquefaciens based on 16S rRNA gene sequencing. The inhibitory activity was stable over a wide range of pH and was fully retained after 30 min at 80°C, after which it decreased gradually at higher temperatures. The activity was sensitive to the proteolytic action of α-chymotrypsin, proteinase-K, and trypsin, indicating its proteinaceous nature. This bacteriocin was active against a broad spectrum of bacteria and the fungus Candida albicans. Direct detection of antimicrobial activity on a sodium dodecyl sulfate-polyacrylamide gel suggested an apparent molecular mass of approximately 5 kDa. Ammonium sulfate precipitation and anion-exchange and gel permeation chromatography integrated with reverse phase-high-performance liquid chromatography were used for bacteriocin purification. Automated N-terminal Edman degradation of the purified RX7 bacteriocin recognized the first 15 amino acids as NH2-X-Ala-Trp-Tyr-Asp-Ile-Arg-Lys-Leu-Gly-Asn-Lys-Gly-Ala, where the letter X in the sequence indicates an unknown or nonstandard amino acid. Based on BLAST similarity search and multiple alignment analysis, the obtained partial sequence showed high homology with the two-peptide lantibiotic haloduracin (HalA1) from Bacillus halodurans, although at least two amino acids differed between the sequences. A time-kill study demonstrated a bactericidal mode of action of RX7 bacteriocin.