Fig 3. The dipeptidyl peptidase IV is not involved in S. suis serotype 2 biofilm formation, while implication of the autolysin is dependent on the sequence type (ST) of the strain used.

Biofilm formation of different wild-type strains and dipeptidyl peptidase IV (DPPIV)- or autolysin (Atl)-deficient mutants in the presence of 2 mg/mL of porcine fibrinogen was evaluated after 24 h of incubation. The optical density (OD) was measured at 575 nm and values corrected using the appropriate controls. Results are expressed as mean ± SEM obtained from three independent experiments. # indicates a significant difference (p < 0.05) between the wild-type ST1 strain P1/7 and ST7 strain SC84 or ST25 strain 89–1591; a (p < 0.01) between the wild-type ST7 strain SC84 and ST25 strain 89–1591; *** (p < 0.001) between the wild-type strain and its Atl-deficient mutant.