Lactic acid concentration of single-species and dual-species 48 h biofilms.

<p>Biofilms were grown under constantly neutral pH or pH-cycling conditions. Before quantification of lactic acid concentration, the biofilms were incubated in the assay medium (pH 7.0), supplemented with 1% glucose for 4 h. Single Sm: <i>S</i>. <i>mutans</i> single-species biofilms; Single So: <i>S</i>. <i>oligofermentans</i> single-species biofilms; Dual: dual-species biofilms. Four replicates were used for lactic acid quantification in each experiment. The experiment was repeated 3 times. * indicates the significant difference between Single Sm and the other two groups (Single So and Dual), <i>p</i> < 0.05.