Abstract:

【Objective】 To investigate the ability of Escherichia coli DH5α outer membrane vesicles（OMVs）transferring the antibiotic resistance gene AmpR among bacteria. 【Method】 The OMVs were extracted by ultracentrifugation; then the morphology, particle size and concentration of OMVs were detected and characterised by transmission electron microscopy, nanoparticle tracking analysis（NTA）and Western blot. Meanwhile, PCR was performed to identify AmpR, an ampicillin resistance gene in OMVs. OMVs were co-incubated and cultured with blank Escherichia coli DH5α, and the bacterial growth on medium with ampicillin was observed, and single colonies were picked to analysize the presence of AmpR by PCR. 【Result】 The average particle size of the extracted vesicles was 125 nm, which was within the range of OMVs particle size, and the OMVs marker protein OmpC was positive, indicating that the extracted vesicles were bacterial OMVs. It was also identified that the ampicillin resistance gene AmpR was in these OMVs. After co-incubation with OMVs, blank E. coli DH5α grew on LB solid plates, and AmpR gene was identified by colony PCR in these bacterial cells. 【Conclusion】 Escherichia coli DH5α with resistant genes can transfer resistance by passing AmpR to surrounding E. coli via outer membrane vesicles OMVs.

Key words: Escherichia coli, outer membrane vesicles（OMVs）, genes with ampicillin resistanc, gene transfer, resistance to drug