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Mobilization of Bacteroides plasmids by Bacteroides conjugal elements
P J Valentine1, N B Shoemaker, A A Salyers
1Department of Microbiology, University of Illinois, Urbana 61801.
Journal of Bacteriology
|March 1, 1988
Summary
The cryptic Bacteroides plasmid pB8-51 is mobilized by multiple tetracycline resistance conjugal elements and the erythromycin resistance plasmid pBF4. These elements facilitate high-frequency transfer of pB8-51 between bacterial strains.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- A cryptic 4.2-kilobase plasmid, pB8-51, is prevalent in colonic Bacteroides species.
- Understanding plasmid mobilization is crucial for bacterial genetics and horizontal gene transfer.
Purpose of the Study:
- To investigate the mobilization of the cryptic Bacteroides plasmid pB8-51 by known Bacteroides conjugal elements.
- To determine if pB8-51 can be transferred between Bacteroides species and to Escherichia coli.
Main Methods:
- Construction of a Bacteroides-Escherichia coli shuttle vector, pVAL-1, containing pB8-51.
- Introduction of pVAL-1 into Bacteroides uniformis 0061 derivatives harboring various Bacteroides conjugal elements.
- Assessment of pVAL-1 mobilization frequency by six tetracycline resistance (Tcr) elements and the erythromycin resistance (Emr) plasmid pBF4.
Main Results:
- All six tested Tcr conjugal elements efficiently mobilized pVAL-1 between Bacteroides strains and to E. coli (10^-3 to 10^-5 frequency).
- Pregrowth in tetracycline significantly enhanced pVAL-1 transfer mediated by Tcr elements (20- to 10,000-fold).
- The Emr plasmid pBF4 mobilized pVAL-1 efficiently between Bacteroides strains but less so to E. coli.
Conclusions:
- The Tcr conjugal elements and pBF4 recognize a specific mobilization region on the pB8-51 plasmid.
- pB8-51 can be mobilized by multiple conjugal elements, indicating potential for horizontal gene transfer within Bacteroides and to other species.