Enhanced Stability of Plasmid pcDNA3.1+ within Salmonella typhimurium by Downregulation of the Ampicillin Resistance Gene Expression
- VernacularTitle:下调bla表达提高pcDNA3?1+在重组菌中的稳定性
- Author:
Xiao-Ming ZHANG
;
Xin-An JIAO
;
Li-Hua TANG
;
Zhi-Ming PAN
;
Jin- HUANG
;
Xiu-Fan LIU
;
- Publication Type:Journal Article
- Keywords:
Salmonella typhimurium, High-copy-number plasmid, Pla smid stability, ?-lactamase
- From:
Microbiology
1992;0(05):-
- CountryChina
- Language:Chinese
-
Abstract:
The high-copy-number plasmid pcDNA3.1+ is unstable within S almonella typhimurium. A novel plasmid pmcDNA3.1+ was constructed by removin g the promoter sequence of ampicillin resistance gene (bla gene) in plasmid pcDNA3.1+. In contrast to pcDNA3.1+, pmcDNA3.1+ was stable within Salmonel la typhimurium SL7207 in LB medium with or without ampicillin. Further experi ments showed the ?-lactamase activity of Salmonella typhimurium SL7207(pmc DNA3.1+) was apparently lowered than that of Salmonella typhimurium SL7207( pcDNA3.1+) and the high ampicillin concentration was maintained longer in LB me dium culturing Salmonella typhimurium SL7207(pmcDNA3.1+). When mice were a dministered with Salmonella typhimurium SL7207(pmcDNA3.1+) intraperitoneall y, more than 95% of Salmonella cells separated from the spleen still harbore d the plasmid pmcDNA3.1+ 7 days later; but 99% of Salmonella cells lost the plasmid pcDNA3.1+ at day 3 in mice innoculated with Salmonella typhimurium SL7207(pcDNA3.1+). By lowering the expression of bla gene, the rapid deco mposition of ampicillin in LB medium was avoided and the metabolic pressure was relieved for the host cells. This method offers a solution for the problem of t he instability of high-copy-number plasmid within Salmonella typhimurium.
