Mutacin H-29B is identical to mutacin II (J-T8).

BACKGROUND: Streptococcus mutans produces bacteriocins named mutacins. Studies of mutacins have always been hampered by the difficulties in obtaining active liquid preparations of these substances. Some of them were found to be lantibiotics, defined as bacterial ribosomally synthesised lanthionine-containing peptides with antimicrobial activity. The goal of this study was to produce and characterize a new mutacin from S. mutans strain 29B, as it shows a promising activity spectrum against current human pathogens. RESULTS: Mutacin H-29B, produced by S. mutans strain 29B, was purified by successive hydrophobic chromatography from a liquid preparation consisting of cheese whey permeate (6% w/v) supplemented with yeast extract (2%) and CaCO3 (1%). Edman degradation revealed 24 amino acids identical to those of mutacin II (also known as J-T8). The molecular mass of the purified peptide was evaluated at 3246.08 +/- 0.1 Da by MALDI-TOF MS. CONCLUSION: A simple procedure for production and purification of mutacins along with its characterization is presented. Our results show that the amino acid sequence of mutacin H-29B is identical to the already known mutacin II (J-T8) over the first 24 residues. S. mutans strains of widely different origins may thus produce very similar bacteriocins.

In vivo activity of mutacin B-Ny266.

OBJECTIVES: The objective of this study was to assess the in vivo activity of mutacin B-Ny266 (a bacteriocin produced by Streptococcus mutans) in order to eventually use it as an antibiotic. METHODS: Intraperitoneal infection was induced with a methicillin-susceptible Staphylococcus aureus strain in mice. Some of the mice were simultaneously injected intraperitoneally with mutacin B-Ny266, some with the vehicle only and some with vancomycin. RESULTS: While there was 70 and 100% mortality in the control groups of mice, no mortality was observed in the mice injected with vancomycin or mutacin B-Ny266. CONCLUSIONS: The results presented here show, for the first time, the in vivo efficacy of a mutacin (B-Ny266) against an experimental intraperitoneal infection by S. aureus in a mouse model.

Improved methods for mutacin detection and production.

Studies of mutacins have always been hampered by the difficulties in obtaining active liquid preparations of these substances. In order to be commercially produced, good mutacin yields have to be obtained, preferably in inexpensive media. The results presented here indicate that mutacins can be produced in supplemented cheese whey permeate. The influence of carbon and nitrogen supplements on mutacin production varied according to the producer strain. The use of CaCO3 as a buffer in batch cultures resulted in improved yields of mutacin in the supernatants. Antimicrobial activity assays were improve by acidification of the diluent (pH 2) and were less variable in peptone water (0.5%). The culture medium consisting of cheese whey permeate (6% w/v), yeast extract (2% w/v) and CaCO3 (1% w/v) was found to be an inexpensive medium for the efficient production of mutacins.

Replacement of trifluoroacetic acid with HCl in the hydrophobic purification steps of pediocin PA-1: a structural effect.

Trifluoroacetic acid (TFA) is a purification contaminant associated with pediocin PA-1 that interferes with Fourier transform infrared spectroscopy structural analysis. As revealed by circular dichroism, its presence affects the structural folding of pediocin. Consequently, we propose a new pediocin PA-1 purification procedure using HCl instead of TFA in all of the hydrophobic steps. This procedural change does not affect the purification yield or the amount of pediocin PA-1 purified. Furthermore, removing HCl, as opposed to TFA, after purification is an easier procedure to carry out. In fact, the removal of TFA requires more experimentation and results in protein loss. Thus, HCl is a good alternative to TFA in pediocin PA-1 purification and can be extended to the purification of other proteins. We also show that TFA-induced structural modifications do not significantly affect the antimicrobial activity of pediocin PA-1.