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Purification and properties of extracellular mutacin, a bacteriocin from Streptococcus sobrinus
J P Loyola-Rodriguez1, I Morisaki, K Kitamura
1Department of Oral Microbiology, Osaka University Faculty of Dentistry, Japan.
Abstract:
Mutacin MT6223, a cell-free bacteriocin produced by Streptococcus sobrinus MT6223, was purified by ammonium sulphate precipitation, chromatofocusing with PBE 94 and column chromatography on SP Sephadex C-25. The specific activity of the purified mutacin was increased 1950-fold with a recovery of 9.7%. The molecular mass of the purified mutacin preparation was estimated to be 6.5 kDa. The mutacin activity was stable from pH 2-7, and was resistant to treatment at 100 degrees C for 20 min. It was inactivated by papain or ficin digestion, and was partially inhibited by alpha-chymotrypsin. The mutacin was found to be active against strains of serotypes c, e and f of Streptococcus mutans and the addition of purified mutacin MT6223 to growing cells of S. mutans MT8148 resulted in a rapid inhibition of incorporation of [3H]thymidine, [3H]uracil or L-[3H]glutamic acid into DNA, RNA or protein, respectively. Specific pathogen-free Fischer rats fed diet 2000 and infected with S. mutans MT8148R showed significantly fewer caries and lower plaque scores when mutacin was administered through drinking water. The present study demonstrates that mutacin MT6223 inhibited the growth of mutans streptococci. Thus, mutacin MT6223 may be a candidate for use in dental caries prevention.
Insights
Mutacin MT6223, a bacteriocin from Streptococcus sobrinus, effectively inhibits the growth of Streptococcus mutans, reducing dental caries and plaque in rats. This suggests its potential for preventing tooth decay.
Area of Science:
- Microbiology
- Biochemistry
- Oral Health
Background:
- Streptococcus mutans are key pathogens in dental caries.
- Bacteriocins offer a potential strategy for controlling bacterial infections.
Purpose of the Study:
- To purify and characterize Mutacin MT6223, a bacteriocin from Streptococcus sobrinus MT6223.
- To evaluate the efficacy of Mutacin MT6223 in preventing dental caries.
Main Methods:
- Purification using ammonium sulphate precipitation, chromatofocusing, and SP Sephadex C-25 chromatography.
- Assessment of mutacin activity, stability (pH, temperature), and susceptibility to proteases.
- In vitro testing against Streptococcus mutans strains and in vivo study in Fischer rats.
Main Results:
- Mutacin MT6223 was purified to a specific activity increase of 1950-fold (9.7% recovery), with a molecular mass of 6.5 kDa.
- The bacteriocin demonstrated stability over a pH range of 2-7 and resistance to heat (100°C for 20 min).
- Mutacin MT6223 inhibited Streptococcus mutans growth and reduced caries and plaque scores in infected rats.
Conclusions:
- Mutacin MT6223 exhibits potent inhibitory activity against mutans streptococci.
- Mutacin MT6223 shows promise as a preventative agent against dental caries.