Plasmid Profile of Locally Isolated Streptococcus mutans in Relation with Mutacin Production

Abstract

The present study was aimed to isolate and identify   Streptococcus  mutans from dental caries, and ability of bacterial isolates for mutacin production and selecting the efficient  producer  isolate and studying  plasmid profile for the selected isolate and its role in mutacin production.  In order  to isolate  Streptococcus  mutans,  80  swab samples were collected from dental  caries of  patients   attends    Al-Dora   health  center  and Al-Zewiya health center in Baghdad  city.    From these samples 80 bacterial isolates were obtained. Results of  identification depending on morphological, cultural and biochemical tests showed that ten of these isolates were belonged  to  Streptococcus mutans,  then results of identification were confirmed by using VITEK-Π identification system.   All isolates were   screened to examine their ability in   mutacin   production.  Plasmid profile of S. mutans S2 was studied to investigate its role in mutacin  production.  Results showed that S.  mutans S2 has only one  plasmid DNA band.  This plasmid was not responsible for mutacin production according to the results of curing experiment by using interchalating   ethidium bromide dye in a concentration   of  800 μg/ml.  Cured cells were still have the ability of  mutacin  production which indicated that this trait is chromosomally encoded.