Plasmid dynamics in a model soil column |
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Authors: | L Sun M J BAZIN J M LYNCH |
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Institution: | Microbiology Group, Life Sciences Division, King's College London, Campden Hill Road, London W8 7 AH;*Microbiology &Crop Protection Department, Horticulture Research International, Worthing Road, Littlehampton, West sussex BN17 6LP, UK |
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Abstract: | Continuous-flow column reactors were used to study the dynamics of plasmid exchange in a structured, thermodynamically open system containing either Enterobacter cloacae or Pseudomonas cepacia , both carrying the transmissible recombinant plasmid R388::Tn1721. Plasmid transfer rates were higher in vermiculite and sterile soil columns supplied with nutrient solution than those in sterile and non-sterile soil columns without input of nutrient solution. For both species, donor and recipient strains took about 5 days to reach their maximum densities in effluents from the columns supplied with nutrient solution. After about 8 day s the donor and transconjugant populations of P. cepacia in the effluent solution decreased exponentially, whereas E. cloacae donor, recipient and transconjugant strains maintained steady-state concentrations. The difference between plasmid stability in the two species may have significant consequences in terms of releasing plasmid-bearing genetically modified microorganisms into the natural environment. The plasmid is persistent in E. cloacae in non-sterile soil even though its transfer to the marked recipient in non-sterile soil was minimal. |
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Keywords: | continuous-flow column reactor Enterobacter cloacae GEM release plasmid transfer Pseudomonas cepacia |
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