Fig. 1

B. licheniformis PF9 protected IPEC-J2 cells against the ETEC F4-induced cytotoxicity. LDH activity in the supernatant was detected by LDH detection kit. The CON group was with no treatment. The groups of ETEC and BL were treated with 10⁶ CFU/mL ETEC F4 alone and 10⁸ CFU/mL B. licheniformis PF9 alone for 3 h, respectively. The groups of ETEC + BL were treated with both ETEC F4 (10⁶ CFU/mL) and B. licheniformis PF9 at the ratio of 1:5, 1:10, 1:25, 1:50, or 1:100 (i.e., 5 × 10⁶, 10⁷, 2.5 × 10⁷, 5 × 10⁷, or 10⁸ CFU/mL) for 3 h, respectively. The data were presented as mean ± SD, n = 4. Different letters represent a significant difference (P < 0.05)