Introduction. Against the backdrop of increasing resistance to conventional antibiotics, bacteriocins represent an attractive alternative, given their potent activity, novel modes of action and perceived lack of issues with resistance.
Aim. In this study, the nature of the antibacterial activity of a clinical isolate of
Streptococcus gallolyticus
was investigated.
Methods. Optimization of the production of an inhibitor from strain AB39 was performed using different broth media and supplements. Purification was carried out using size exclusion, ion exchange and HPLC. Gel diffusion agar overlay, MS/MS, de novo peptide sequencing and genome mining were used in a proteogenomics approach to facilitate identification of the genetic basis for production of the inhibitor.
Results. Strain AB39 was identified as representing
Streptococcus gallolyticus
subsp.
pasteurianus
and the successful production and purification of the AB39 peptide, named nisin P, with a mass of 3133.78 Da, was achieved using BHI broth with 10 % serum. Nisin P showed antibacterial activity towards clinical isolates of drug-resistant bacteria, including methicillin-resistant
Staphylococcus aureus
, vancomycin-resistant
Enterococcus
and penicillin-resistant
Streptococcus pneumoniae
. In addition, the peptide exhibited significant stability towards high temperature, wide pH and certain proteolytic enzymes and displayed very low toxicity towards sheep red blood cells and Vero cells.
Conclusion. To the best of our knowledge, this study represents the first production, purification and characterization of nisin P. Further study of nisin P may reveal its potential for treating or preventing infections caused by antibiotic-resistant Gram-positive bacteria, or those evading vaccination regimens.
Expression, Purification, and Characterization of a Novel Hybrid Peptide with Potent Antibacterial Activity