The Production And Application In Oral Products Of Mutanolysin

Streptomyces sp.G4 posessing high lytic activity was isolated from soils by the double layer plate containing intact cells of Streptococcus mutans.According to the research of Morphological,cultural,physiological properities,composition of cell wall and 16srDNA sequences,G4 was classified into Streptomyces globisporus.A mutant strain-Stremptomyces globisporus G4-3 with high field of mutanolysin was obtained from Stremptomyces globisporus G4 by UV and EMS mutation,and screened by using agar plate screening techniques.The enzyme activity of G4-3 was about 1.1 times of that of G4 and the fermentation was shorted 1 days.By using single factor and orthogonal test,the optimal fermentation medium consisted of components as follows:3% sucrose,1.25% soybean meal,0.25% meat extract,0.6% NaCl,0.05% K2HPO4,0.1% NaH₂PO₄,0.01% CaCl₂.The study of the optimal cultivation condition indicatied that incubation time had significant effect on the production of the mutanolysin.The optimal temperature and pH for the lytic activity was 55℃and 6.5.In the circumstance with pH4-10,the mutanolysin was easy to keep activity.The lytic activity was very sensitive to the variety of the strengthen.Most matal icons,chelating agent,moniodoacetic acid and SDS inhibited the lytic activity,whereas non-ionic surfactant such as Triton X-100,Tween-80 could stimulate the activity.The mutanolysin had a broader bacteriolytic spectrum than egg-white lysozyme,possessing high activity against most of G+ bacteria and a few of G^- bacteria,especially against S.mutans.Two lytic enzyme,A1and A2,had been purified to give a single band on SDS-PAGE from the mutanolysin.The molecular weights were about 14795 and 23780 for A1 and A2.Isoelectric point detected by IEF was about 9.3 and 9.8,respectively.Finally, to make feasibility analysis and researches of application of the mutanolysin in toothpaste,found that toothpaste components,such as ionic surfactants, thickener and adhesive reagent,inhibited most of the lytic activity,but the non-ionic surfactant can effectively remove this inhibition.