[WS5-3] Comprehensive analysis of bacteriocins in Streptococcus mutans
It is well known that Streptococcus mutans produce bacteriocins which show antibacterial activity against several bacteria. Up to date, many bacteriocins have been reported in S. mutans. However, these bacteriocins have not been precisely understood. In this study, we isolated 125 S. mutans strains from volunteers and determined the whole genome sequence. Based on the genome analysis, we investigated the distribution of each bacteriocin gene (mutacin I to IV, K8 and Smb). Among 125 strains, single bacteriocin gene positive, double positive and triple positive strains were 84 (65.1%), 26 (20.2%), and 5 (3.9%), respectively. Then, the antibacterial activity against oral streptococci and other oral bacterial species was investigated by using each single positive strain. The pattern of the antibacterial activity in each bacteriocin gene positive strain was different although some strains did not show the activity due to the mutations. These results indicate that individual S. mutans has a unique antibacterial activity affecting the bacterial composition in oral cavity.