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Monitoring Intraspecies Competition in a Bacterial Cell Population by Cocultivation of Fluorescently Labelled Strains
Published on: January 18, 2014
Population dynamics and gene transfer in genetically modified bacteria in a model microcosm
A K Lilley1, M J Bailey, M Barr
1Molecular Microbial Ecology Group, Centre for Ecology and Hydrology, Mansfield Road, Oxford OX1 3SR, UK.
Molecular Ecology
|November 25, 2003
Summary
Gene transfer in plant-colonizing bacteria depended on insertion location. Chromosomal insertion boosted Pseudomonas populations, while plasmid transfer occurred in the phyllosphere and rhizosphere, impacting bacterial fitness.
Area of Science:
- Microbiology
- Ecology
- Genetics
Background:
- Horizontal gene transfer (HGT) is crucial for bacterial adaptation and evolution.
- Understanding HGT mechanisms and their impact on host fitness in complex environments is vital.
- Pseudomonas species are important plant-associated bacteria with significant ecological roles.
Purpose of the Study:
- To investigate the horizontal transfer of a neutral gene cassette and its effects on host fitness.
- To compare the outcomes of gene insertion into different genomic locations (chromosome vs. plasmid) in Pseudomonas.
- To assess gene transfer and bacterial population dynamics in a model plant-associated ecosystem.
Main Methods:
- A reporter gene cassette (kanamycin resistance, xylE) was inserted into three distinct genomic loci of Pseudomonas fluorescens SBW25R: chromosome, chromosome with phage, and a natural plasmid (pQBR11).
- Engineered bacteria were applied as seed dressings to Stellaria media (chickweed) in microcosm chambers with model communities.
- Bacterial population densities, gene transfer events (phyllosphere, rhizosphere), and plasmid acquisition were monitored throughout plant development.
Main Results:
- Gene transfer to pseudomonads was observed only when the cassette was on the plasmid (pQBR11).
- Bacterial populations with chromosomal insertion consistently showed higher densities than controls.
- Plasmid acquisition from indigenous bacteria occurred in control and chromosomal insertion treatments, coinciding with plant maturation.
Conclusions:
- The genomic location of gene insertion significantly influences bacterial population dynamics and gene transfer success.
- Chromosomal insertion of neutral genes can enhance host fitness and population density in plant environments.
- Plasmid-mediated gene transfer is a significant factor in the phyllosphere and rhizosphere, influenced by host plant development.
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