title: Antimicrobial peptide isolated from Bacillus amyloliquefaciens K14 revitalizes its use in combinatorial drug therapy.
abstract: The present study was performed to evaluate the antibacterial activities of an antimicrobial peptide (CSpK14) and the synergies thereof with β-lactams against vancomycin-resistant Staphylococcus aureus (VRSA) and Enterococci (VRE). Our strain was isolated from fermented food (kimchi), which is 99.79 % homologous with Bacillus amyloliquefaciens subsp. plantarum FZB42(T). CSpK14 was purified to homogeneity by diammonium sulfate precipitation, concentration, dialysis, and followed by two-stage chromatographic separation, i.e., Sepharose Cl-6B and Sephadex G-25 chromatography, and had a molar mass of ~4.6 kDa via Tricine SDS-PAGE and in situ examination. It was stable at pH 6.0-11.5 and temperature up to 80 °C. In addition, it was also stable with various metal ions, solvents, and proteases. The N-terminal amino acid sequence was H-Y-D-P-G-D-D-S-G-N-T-G and did not show any significant homology with reported peptides. However, it shows some degrees of identity with alpha-2-macroglobulin and ligand-gated channel protein from different microorganisms. CSpK14 significantly reduced the minimum inhibitory concentrations (MICs) of β-lactams and had no effect on non-β-lactams against VRSA and VRE. MICs of CSpK14/oxacillin and CSpK14/ampicillin were reduced by 8- to 64-fold and 2- to 16-fold, respectively. The time killing assay between CSpK14/oxacillin (2.29-2.37 Δlog10CFU/mL at 24 h) and CSpK14/ampicillin (2.30-2.38 Δlog10CFU/mL at 24 h) being >2-fold and fractional inhibitory concentration index ˂0.5 revealed synergy. Furthermore, the biofilms formed by VRSA and VRE were reduced completely. CSpK14 was simple to purify, had low molecular mass, was stable over a wide pH range or tested chemicals, had broad inhibitory spectrum, and possessed potent synergistic antimicrobial-antibiofilm properties. CSpK14 synergistically enhanced the efficacy of β-lactams and is therefore suitable for combination therapy.
authors: Department of Pharmacy, College of Pharmacy, Chosun University, Gwangju, 501-759, South Korea.
authors: Sudip
authors: S
authors: Regmi
authors: Department of Pharmacy, College of Pharmacy, Chosun University, Gwangju, 501-759, South Korea.
authors: Yun Hee
authors: YH
authors: Choi
authors: Department of Pharmacy, College of Pharmacy, Chosun University, Gwangju, 501-759, South Korea.
authors: Yoon Seok
authors: YS
authors: Choi
authors: Department of Pharmacy, College of Pharmacy, Chosun University, Gwangju, 501-759, South Korea.
authors: Mi Ri
authors: MR
authors: Kim
authors: Department of Pharmacy, College of Pharmacy, Chosun University, Gwangju, 501-759, South Korea. jcyu@chosun.ac.kr.
authors: Jin Cheol
authors: JC
authors: Yoo
mesh_terms: D000595:Amino Acid Sequence; D000667:Ampicillin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology*; D000069977:Bacillus amyloliquefaciens / Q000145:classification / Q000276:immunology / Q000378:metabolism*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002852:Chromatography, Ion Exchange; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology*; D010802:Phylogeny; D055550:Protein Stability; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D020713:Vancomycin Resistance / Q000187:drug effects; D065507:Vancomycin-Resistant Enterococci / Q000187:drug effects / Q000254:growth & development
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D000667:Ampicillin; D010068:Oxacillin