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Loss of R factors promoted by bacteriophage M13 and the M13 carrier state
Abstract:
The infection of different Hfr strains of Escherichia coli bearing derepressed R factors of the fi(+) or fi(-) type can result in the loss of the R factor and the conversion of the infected cells to the R(-) state. This extends earlier observations on the elimination of F' factors by bacteriophage M13 infection. Variability in the efficiency of this conversion can arise because of genetic factors independent of the R factor being eliminated. A fraction of the infected but unconverted R(+) cells were M13 carrier strains. The carrier state had an intracellular basis, and single R(+) cells could maintain the carrier state.
Insights
Bacteriophage M13 infection can eliminate R factors from Escherichia coli, converting R(+) cells to R(-). Genetic factors influence elimination efficiency, and some cells become M13 carriers maintaining the R factor intracellularly.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- R factors (resistance plasmids) confer antibiotic resistance to bacteria.
- Bacteriophage M13 infection is known to eliminate certain plasmids like F' factors.
- The effect of M13 on R factor elimination in Escherichia coli was not fully understood.
Purpose of the Study:
- To investigate the elimination of derepressed R factors (fi(+) or fi(-)) in Escherichia coli by bacteriophage M13 infection.
- To explore factors influencing the efficiency of R factor elimination.
- To characterize the M13 carrier state in R(+) cells.
Main Methods:
- Infection of various Hfr strains of Escherichia coli carrying derepressed R factors with bacteriophage M13.
- Assessment of R factor loss and conversion to the R(-) state.
- Identification and characterization of M13 carrier strains among unconverted R(+) cells.
Main Results:
- M13 infection successfully eliminated R factors in a significant proportion of infected Escherichia coli cells, resulting in R(-) conversion.
- Variability in elimination efficiency was observed, suggesting the involvement of host genetic factors independent of the R factor.
- A fraction of infected, unconverted R(+) cells became M13 carrier strains, maintaining the R factor intracellularly.
Conclusions:
- Bacteriophage M13 infection is an effective method for eliminating R factors in Escherichia coli.
- Host genetics play a role in modulating the efficiency of R factor elimination by M13.
- An intracellular carrier state for M13 and R factors can be established and maintained within single bacterial cells.