Table 1.
Strains used in this study.
Fig 1.
Direct assay of bacteriocin-producing S. epidermidis against braRS-inactivated S. aureus.
The antibacterial activity of bacteriocin-producing S. epidermidis was evaluated by the direct assay using S. aureus MW2 braRS-inactivated mutant.
Fig 2.
Gene map of the epidermin-carrying plasmid in KSE56.
(a) Epidermin-encoding plasmid from KSE56 (pEpi56). ORFs are shown as arrows, indicating the orientation of transcription. The arrow numbers indicate the ORF number displayed in Table 2. Colors indicate the classification of gene function. (b) Bacteriocin-coding region (KSE56 epidermin). The bacteriocin-coding region from pEpi56 was compared with pTu32 epiP-Y’ (accession number X62386) and pTu32 epiT"-G (accession number U77778). Striped blue arrows indicate truncated epiT.
Table 2.
Genes in pEpi56.
Fig 3.
Nukacin-carrying plasmids and amino acid sequences of nukacin.
(a) Nukacin-encoding plasmid from KSE650 (pNuk650) and the comparison with pIVK45. (b) Amino acid alignment of nukacin ISK-1, nukacin 3299, nukacin KQU131, nukacin IVK45 and nukacin KSE650.
Table 3.
Genes in pNuk650.
Fig 4.
Purification of epidermin and nukacin KSE650 by reverse phase-HPLC and mass determination by ESI-MS.
(a) RP-HPLC chromatogram of epidermin and nukacin KSE650. The arrow shows the peak corresponding to epidermin (upper) or nukacin KSE650 (lower). (b) Mass determination of epidermin (upper) or nukacin KSE650 (lower) by ESI-MS. Several isotopic peaks in each mass/charge (m/z) state.
Fig 5.
Antibacterial activity of KSE56, KSE650, and their plasmid-deleted strains.
Direct assays were performed using KSE56, KSE650, and their plasmid-deleted strains. S. hominis was used as an indicator strain.
Table 4.
Antibacterial activity of KSE56 and KSE650 against various bacterial species.
Table 5.
Minimum antibacterial dose of purified epidermin and nukacin KSE650.
Fig 6.
The proportion of S. epidermidis KSE1, KSE56, and KSE650 in co-culture with M. luteus.
Co-culture assays were performed according to the method described in the Materials and methods. Post hoc multiple comparisons were made using Tukey’s test.
Fig 7.
Structure of nukacin ISK-1 and nukacin KSE650.
The mature peptide sequences of nukacin ISK-1 and nukacin KSE650 are shown. The deduced calculated mass of mature nukacin KSE650 is consistent with that observed by ESI-MS. The structure is identical to that of nukacin ISK-1, except for the residues indicated by gray circles. Dhb, Ala-S-Ala, and Abu-S-Ala indicate dehydrobutyrine, lanthionine, and 3-methyllanthionine respectively.