Integrated metabolomic and transcriptomic study of Klebsiella pneumoniae strain: possible inhibitory mechanism of Rutin on strain growth

10 mL pre-incubated culture medium was centrifuged for collection of bacteria cells. The metabolites identification and quantification were also conducted by Beijing iGeneTech Biotechnology Company. Briefly, the freeze-dried samples were mashed with liquid nitrogen, and 50 mg of powder for each sample was transferred into a 1.5 mL EP tube containing 5 mL precooled methanol/water (V:V=3:1) and subjected to vigorous vortexing. Each sample point had 3 independent biological replicates. All samples were extracted at 4˚C overnight. Then, the samples were centrifuged at 13,000 rpm for 15 min at 4˚C and the filtered supernatant (0.22 μm membrane filter) was blow-dried with nitrogen. The samples were redissolved with 50μL isopropanol/acetonitrile/water (V:V:V=2:7:1) and extracted by centrifugation before LC-MS/MS analysis.