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Effect of R-plasmid RP1 on surface hydrophobicity of Proteus mirabilis
1Department of Pharmaceutical Sciences, Aston University, Birmingham, UK.
Abstract:
The presence of R-plasmid RP1, as well as the conditions of growth, affected the surface hydrophobicity of a clinical isolate of Proteus mirabilis. However, results depended upon the method of assessment. Stationary phase plasmid-containing cells appeared to be less hydrophobic than plasmid-free cells when hydrophobicity was measured by the contact angle method, but more hydrophobic when measured by bacterial adherence to hydrocarbons or hydrophobic interaction chromatography. Cells growing in a chemostat differed in hydrophobicity from stationary phase cells and results varied with the growth rate. Plasmid-mediated effects were greatest in iron-depleted cells, and differences between plasmid-containing and plasmid-free cells were virtually eliminated by pre-treatment with antiserum.
Insights
The R-plasmid RP1 influences Proteus mirabilis surface hydrophobicity, but findings vary with measurement methods and growth conditions. Iron depletion and antiserum treatment further modify these plasmid-mediated effects.
Area of Science:
- Microbiology
- Bacterial genetics
Background:
- Surface hydrophobicity is a key bacterial characteristic influencing adhesion and pathogenesis.
- Plasmids can alter bacterial surface properties, impacting their interaction with the environment.
- Proteus mirabilis is an opportunistic pathogen where understanding surface properties is clinically relevant.
Purpose of the Study:
- To investigate the impact of R-plasmid RP1 on the surface hydrophobicity of Proteus mirabilis.
- To determine how different growth conditions and assessment methods influence plasmid-mediated hydrophobicity changes.
- To explore the role of iron availability and antiserum in modulating these effects.
Main Methods:
- Bacterial culture of Proteus mirabilis with and without R-plasmid RP1 under various growth conditions (stationary phase, chemostat).
- Assessment of surface hydrophobicity using multiple techniques: contact angle method, bacterial adherence to hydrocarbons (BATH), and hydrophobic interaction chromatography (HIC).
- Evaluation of plasmid-mediated effects under iron-depleted conditions and after antiserum pre-treatment.
Main Results:
- R-plasmid RP1 presence significantly affected Proteus mirabilis surface hydrophobicity, with results dependent on the assessment method.
- Stationary phase cells showed contradictory hydrophobicity results between contact angle and BATH/HIC methods.
- Chemostat-grown cells exhibited different hydrophobicity profiles compared to stationary phase cells, varying with growth rate. Plasmid effects were amplified in iron-depleted conditions and reduced by antiserum.
- Differences between plasmid-containing and plasmid-free cells were largely abolished by antiserum pre-treatment.
Conclusions:
- Bacterial surface hydrophobicity is complex and method-dependent, particularly when influenced by plasmids like RP1.
- Growth conditions, including nutrient availability (iron) and growth phase, significantly modulate plasmid-associated changes in hydrophobicity.
- Antiserum can effectively mask or neutralize plasmid-mediated surface alterations in Proteus mirabilis.