Effect of deleting five “key” transcriptional regulators and sensitivity of the cysR deletion mutant to carolacton treatment. (A) Inhibition of viability caused by carolacton treatment was tested for the biofilms of gene deletion mutants of 5 key transcriptional regulators identified from network analysis. The inhibition of viability was determined by live/dead staining of 20 h-old static biofilms of mutant, wild type and cysR complementation strains under carolacton treatment and is expressed as inhibition of the green/red fluorescence ratio. The bars show the mean of three independent biological replicates. (B) The effect of carolacton treatment on the number of colony forming units (cfu’s) of biofilms of the S. mutans UA159 wildtype and cysR gene deletion mutant was also investigated. The Cfu experiment was repeated in two biological replicates. The sequences of primers used for generating the deletion mutants are given in Additional file 9.