Bacteriocins are antimicrobial substances produced by several bacteria, which can kill phylogenetic-related bacteria and facilitate their survival in an ecologic environment. Dental caries is an infectious, chronic, and transmissible disease, which is mainly caused by S.mutans (MS). MS is a gram positive bacteria capable to produce bacteriocins, which may play an important role in the pathogenesis of dental caries. OBJECTIVES: We evaluated the ability to produce bacteriocins of MS strains from Healthy individuals (HI) and patients with dental caries (PC) METHODS: 83 MS strains from HI and PC were isolated and identified by biochemical profile and enzymatic biotypifying. Bacteriocins production was tested using agar double layer method in several combinations of MS strains from HI, PC and reference strains. Different cariogenic and non cariogenic bacteria were also evaluated RESULTS: All MS strains from both groups (PC and HI) produced bacteriocins against some MS strain and/or related strains (S. sobrinus, S. sanguis, S. oralis, S. rattus and, S. gordonni). The MS strains from HI showed a significant higher bacteriocin production regard PC strains*. There was not a bacteriocin-specific effect for cariogenic and non cariogenic strains. CONCLUSIONS: MS strains from HI were significant higher producers of bacteriocins than strains from PC, which was associated with their major capacity to inhibit growth of cariogenic and non cariogenic strains. These results suggest that bacteriocins could be involved in the permanence of certain MS strains in oral cavity of HI, which potentially may be inhibiting the growth of cariogenic MS strains in a biologic control fashion. *Mann Whitney, p<0.05

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