FIG. 4.

Regulation of mutacin IV production by SMu486 in S. mutans. (A) Deferred antagonism assay for mutacin IV production. S. mutans cultures were stabbed into THY agar and incubated overnight at 37°C under microaerophilic conditions. The plates were overlaid with soft agar containing the indicator strain. The zone of inhibition of the indicator strains was evaluated after overnight incubation. (B) Semiquantitative RT-PCR results showing the expression of nlmA and nlmT by the wild type (UA159), the ΔSMu486 mutant (IBS148), and the ΔSMu486 mutant complemented with pIB55 (IBS148/pIB55). The data are representative of RT-PCR analyses resulting from at least two different RNA isolations.