Studies with bioengineered Nisin peptides highlight the broad-spectrum potency of Nisin V.
Bottom Line: In contrast, Nisin V displayed increased potency against all targets tested including hVISA strains and the hyper-virulent Clostridium difficile ribotype 027 and against important food pathogens such as Listeria monocytogenes and Bacillus cereus.Significantly, this enhanced activity was validated in a model food system against L. monocytogenes.We conclude that Nisin V possesses significant potential as a novel preservative or chemotherapeutic compound.
Affiliation: Department of Microbiology, University College Cork, Cork, Ireland.Show MeSH
Related in: MedlinePlus
Mentions: While MIC analysis can illustrate the increased specific activity of the bioengineered peptides compared with Nisin A, they are end‐point assays and cannot reveal the more subtle details of the impact of an antimicrobial on bacterial viability that are apparent when growth curve analysis is performed. Furthermore, because such assays are based on the ability of the antimicrobial to retard growth, they do not provide an accurate insight into its ability to kill the pathogen. To address this issue, two of the indicators employed above, S. agalactiae ATCC 13813 and L. monocytogenes EGDe, were selected for further growth and kill analysis with a view to comparing the results with MIC values. For S. agalactiae ATCC 13813, at the concentration of peptide employed (0.04 mg l−1; Fig. 2A), Nisin A caused a slight delay in growth relative to the non‐Nisin‐containing control. Identical concentrations of the Nisin V and Nisin T resulted in a greater lag time, with the lag time being greatest when Nisin T was employed. Thus while the twofold dilutions of peptide employed for MIC determination did not reveal a difference in the specific activity of Nisin V and Nisin T against S. agalactiae ATCC13813, it is apparent from growth curve assays with equimolar concentrations of peptide that Nisin T is, in fact, slightly more potent. Thus while Nisin V is typically more potent than Nisin T, this result coupled with MIC data for L. lactis HP, reveals that in some select instances Nisin T is the more active of the two. An investigation of the growth of L. monocytogenes EGDe in the presence of sublethal quantities (4.19 mg l−1) of the Nisin peptides (as previously employed by Begley et al., 2006), and a non‐Nisin‐containing control, highlighted the greater potency of Nisin V as evident from a greatly extended lag. As expected, on the basis of MIC analysis, Nisin A and Nisin T did not differ dramatically (Fig. 2B).
Affiliation: Department of Microbiology, University College Cork, Cork, Ireland.