Objective:

2

To investigate the effect of low concentration of Wenyang Tonglin Decoction (WTD) on the binding conditions of R45 plasmid conjugative transfer under liquid phase conjugation and its mechanism.

Methods:

2

Escherichia coli

CP9 (R45) and

Staphylococcus aureus

RN450RF were cultured in medium containing WTD

and their minimum inhibitory concentration (MIC) values were obtained. Using promoter fusion technology

E. coli

CP9 (R45) containing a promoter fusion was obtained. β-Galactosidase activity of TrfAp and TrbBp was tested

and the mRNA expression of regulatory factors (TrbA

KorA

and KorB) was detected by real-time fluorescent quantitative polymerase chain reaction.

Results:

2

The MIC of

E. coli

CP9 (R45) was 400 g/L and that of

S. aureus

RN450RF was 200 g/L. When the drug concentration in the culture medium was 200 g/L

the highest number of conjugants was (3.47±0.20)×10

7

CFU/mL. At 90 h of conjugation

the maximum number of conjugants was (1.15±0.06)×10

8

CFU/mL. When the initial bacterial concentration was 10

8

CFU/mL

the maximum number of conjugants was (3.47±0.20)×10

7

CFU/mL. When the drug concentration was 200 g/L

the β-galactosidase activity of TrfAp and TrbBp significantly increased; the relative quantification of TrbA

KorA and KorB were significantly inhibited.

Conclusion:

2

Low concentration of WTD promoted the development of bacterial resistance by affecting promoters and inhibiting the expression of regulatory factors.