Analysis of the role of CrfP in the lytic process. A Decreases in the turbidity of S. suis serovar 2 ZY05719 treated with different doses of CrfP were observed at five time points: 15 min, 30 min, 45 min, 60 min and 75 min. CrfP was used, and the turbidity showed a sharp decrease within 15 min. After incubation for 60 min, the lytic activity of 20 μg/mL CrfP was very close to that of 40 μg/mL CrfP; therefore, we selected 20 μg/mL as the optimal final concentration of CrfP. B Only the CHAP domain-containing protein was added to bacteria, but no lytic ability was observed within the incubation period. C ZY05719 cells were treated with CrfP (20 μg) for 1 h, and the live bacterial counts were determined. D Binding of purified exogenous SH3b–GFP fusion protein to the surface of S. suis cells. Fluorescence micrograph showing S. suis cells stained with the DNA-specific fluorescent probe DAPI (blue) and the fusion protein (green). GFP protein was used as the control. The white bars represent 10 μm.