Fig. 7.

Effect of calcium on the expression of Ab-related genes. The calcium supplementation final concentrations were as follows: Group a, 1.4 mmol/L; Group b, 2.4 mmol/L; Group c, 3.4 mmol/L; Group d, 4.4 mmol/L; Group control I: calcium final concentration was 0 mmol/L (with EDTA treatment); Abiotic environment: bacteria only were cultured in plates containing RPMI 1640 medium; Cellular environment: bacteria were cultured in epithelial cell covered plates (80–90% cell confluence) containing RPMI 1640 medium. The recA gene was used as an internal reference. The relative changes of Ab related gene expression between the experimental groups and control I group were calculated by the 2^-△△Ct method