PCR verifications of the unique presence or absence of TCS genes. The unique absence of TCS-3 and TCS-9 in S. sorbrinus DSM20742 are demonstrated by showing the absences of the HK of its TCS-3 and the HK and RR of its TCS-9, in contrast to the presence of the corresponding genes in other strains, as exemplified in S. mutans UA159 and S. ratti DSM20564. The absence of TCS-13 and the presence of TCS-18 in S. ratti DSM20564 are presented in contrast to S. mutans UA159 and S. sorbrinus DSM20742. The unique presence of TCS-15 in S. mutans NCTC11060 was verified using two forward primers. The sequences of the primers used for PCR are provided in the Materials and Methods section.