FIG 1. The PdeA deficiency increased c-di-AMP levels and promoted biofilm formation of S. mutans.

(A) Detection of bacterial c-di-AMP levels. Cell lysates of wild type, the pdeA mutant and the complemented strain were used to determine intracellular c-di-AMP levels by competitive ELISA. Data were normalized by bacterial growth OD₄₇₀ of the cultures. (B) Biofilm formation by the pdeA mutant. Biofilm mass of wild type, the pdeA mutant and the complemented strain were determined using crystal violet staining assay and normalized to bacterial growth by OD₅₆₂/OD₄₇₀. Means of three independent experiments are shown. Error bars denote the SEM. *, P < 0.01 of Student’s t test using Prism 5.0.