F 4500 uorescence spectrophotometer

To evaluate the pro-/synbiotic effect on gut barrier integrity, FITC-dextran assay and serum endotoxin level detection kit were used [21] .
On the day of sacri ce, mice were subjected to fasting for 4 h, followed by intragastric injection with FITCdextran tracer (0.6 mg/g body weight; Cat. No. 46944, Sigma-Aldrich) dissolved in 0.1 mL PBS. After 3 h, sera samples were collected to measure the intensity value of FITC uorescence at an excitation wavelength of 490 nm and an emission wavelength of 530 nm using a Hitachi F-4500 uorescence spectrophotometer. The samples were diluted in PBS to plot a standard curve. The measurement has been conducted a minimum of three times per sample.
Serum endotoxin levels were detected using the Pierce TM Chromogenic Endotoxin Quant Kit (Thermo Fisher Scienti c, Waltham, MA) according to the manufacturer's protocol. 50 μl of diluted serum samples were tested by a colorimetric method.

The total reactive oxygen species (ROS) released from MRSA treated with the different concentrations of antibacterial protein CB6-C (8 µg/mL, 16 µg/mL, 32 µg/mL and 64 µg/mL) was probed with an ROS assay kit (Nanjing Jiancheng Bioengineering Institute, Jiangsu, China), which was performed according to the manufacturer's instructions. No treatment with antibacterial protein CB6-C was performed as the negative control for ROS production. The uorescence value of each sample was measured with an F4500 uorescence spectrophotometer (emission λ = 525 nm, excitation λ = 488 nm) (Hitachi, Tokyo, Japan).