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Curing action of sodium dodecyl sulfate on a Proteus mirabilis R+ strain
Abstract:
Growth of Proteus mirabilis harboring R100-1 (fi(+)drd str(r)cml(r)tet(r)sul(r)) factors in Penassay broth containing sodium dodecyl sulfate (SDS) leads to the loss of all or part of the genetic elements in high frequencies. In media containing SDS at concentrations as low as 0.03%, both lysis of R(+) cells and elimination of the R factors occur at high frequencies. Appearance of drug-susceptible cells in R(+) cultures occurs during the exponential phase of growth; however, the frequencies of susceptible cells increase substantially after the culture reaches the stationary phase. Reconstruction experiments, coupled with other observations, suggest that the major factor in altering the frequency of drug-susceptible variants is the greater resistance of the variants to the lytic action of SDS. This resistance correlates in most cases with the loss of the transfer functions in the resistance transfer factor.
Insights
Sodium dodecyl sulfate (SDS) treatment of Proteus mirabilis with R100-1 factors causes high-frequency loss of genetic elements. Variants resistant to SDS-induced lysis, often lacking transfer functions, increase significantly during stationary phase.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Proteus mirabilis is a bacterium known to harbor R factors, which confer antibiotic resistance.
- R factors, such as R100-1, are plasmids that can be transferred between bacteria.
- Sodium dodecyl sulfate (SDS) is a detergent with antimicrobial properties.
Purpose of the Study:
- To investigate the effect of SDS on the stability of R100-1 factors in Proteus mirabilis.
- To understand the mechanisms behind the loss of R factors and the emergence of drug-susceptible variants.
Main Methods:
- Growth of Proteus mirabilis harboring R100-1 in Penassay broth with varying concentrations of SDS.
- Monitoring the frequency of R factor loss and drug-susceptible cells during different growth phases.
- Conducting reconstruction experiments to assess the role of SDS resistance in variant selection.
Main Results:
- SDS at concentrations as low as 0.03% induced high-frequency lysis of R(+) cells and elimination of R factors.
- Drug-susceptible variants appeared during the exponential phase and increased substantially in the stationary phase.
- SDS-resistant variants, often with lost transfer functions, were more frequent due to their resistance to SDS-induced lysis.
Conclusions:
- SDS is a potent agent for inducing the loss of R100-1 factors in Proteus mirabilis.
- The emergence of drug-susceptible variants is primarily driven by their increased resistance to SDS.
- Loss of transfer functions in the resistance transfer factor correlates with SDS resistance.