Effects of Klebsiella pneumoniae on mitochondrial membrane potential (MMP) in bovine mammary epithelial cells (bMECs). bMECs incubated with Klebsiella pneumoniae (strain HLJ-D2 or HB-AF5) for 0, 1, 3, 6 and 12 h were collected for assessment of mitochondrial membrane potential (MMP) using JC-1 staining. Data are mean ± SD of three independent experiments. FITC: Green light channel, PE: red light channel. Statistical significance indicated by: ∗ P < 0.05, ∗ ∗ P < 0.01 for comparisons of HLJ-D2 and HB-AF5 to the control group, and #P < 0.05, ##P < 0.01 for comparisons between HLJ-D2 and HB-AF5 at the same timepoint.