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Persistence of plasmid RP4 in Pseudomonas putida and loss of its expression of antibiotic resistance in a groundwater microcosm

Bengtsson, Göran LU ; Fossum, A and Lindqvist, R (2004) In Atmospheric Environment 36(6). p.999-1008
Abstract
We examined the stability of plasmid RN and its expression of antibiotic-resistance genes in suspended and sorbed Pseudomonas putida in aquifer microcosms. Test tubes containing different proportions of sterilized aquifer soil and groundwater were inoculated with bacteria and incubated for up to 26 d. Serial dilutions were made to agar plates with or without antibiotics, to quantify the functional stability of the plasmid. The structural integrity of RN was examined by plasmid extraction, digestion with restriction enzymes, and agarose gel electrophoresis. The plasmid-borne resistance gene expression disappeared in 80-90% of the cells during day 1 of incubation in aquifer soil and then remained at that frequency throughout the experiment.... (More)
We examined the stability of plasmid RN and its expression of antibiotic-resistance genes in suspended and sorbed Pseudomonas putida in aquifer microcosms. Test tubes containing different proportions of sterilized aquifer soil and groundwater were inoculated with bacteria and incubated for up to 26 d. Serial dilutions were made to agar plates with or without antibiotics, to quantify the functional stability of the plasmid. The structural integrity of RN was examined by plasmid extraction, digestion with restriction enzymes, and agarose gel electrophoresis. The plasmid-borne resistance gene expression disappeared in 80-90% of the cells during day 1 of incubation in aquifer soil and then remained at that frequency throughout the experiment. The RP4 plasmid was present in cells without antibiotic-resistance gene expression, indicating that the observed loss of plasmid-encoded activity was most likely due to a reduction in expression of the resistance genes. The increased growth rate in groundwater amended with glucose and phosphate had no significant influence on plasmid loss or antibiotic-resistance expression, suggesting that plasmid loss and antibiotic-resistance expression were independent of the growth rate. Most of the reduction of resistance gene expression was associated with the presence of soil particles, and 70% of the resistance expression was retained in bacteria incubated for 1 d in groundwater alone. Bacteria sorbed to the soil particles had a lower frequency of expression of resistance genes than suspended bacteria, but the difference was not caused by sorbed inorganic or organic chemicals. Resistance gene expression was partly recovered in suspended bacteria after in vitro exposure to the antibiotics and after first isolating on agar without antibiotics and then replica plating to agar containing the antibiotics. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Atmospheric Environment
volume
36
issue
6
pages
999 - 1008
publisher
Elsevier
external identifiers
  • wos:000221848900014
  • scopus:2442536979
ISSN
1352-2310
DOI
10.1016/j.soilbio.2004.02.015
language
English
LU publication?
yes
id
96a9f592-a93d-4975-8386-f3c0cdade1fa (old id 135838)
date added to LUP
2007-06-27 08:28:29
date last changed
2017-01-01 07:01:04
@article{96a9f592-a93d-4975-8386-f3c0cdade1fa,
  abstract     = {We examined the stability of plasmid RN and its expression of antibiotic-resistance genes in suspended and sorbed Pseudomonas putida in aquifer microcosms. Test tubes containing different proportions of sterilized aquifer soil and groundwater were inoculated with bacteria and incubated for up to 26 d. Serial dilutions were made to agar plates with or without antibiotics, to quantify the functional stability of the plasmid. The structural integrity of RN was examined by plasmid extraction, digestion with restriction enzymes, and agarose gel electrophoresis. The plasmid-borne resistance gene expression disappeared in 80-90% of the cells during day 1 of incubation in aquifer soil and then remained at that frequency throughout the experiment. The RP4 plasmid was present in cells without antibiotic-resistance gene expression, indicating that the observed loss of plasmid-encoded activity was most likely due to a reduction in expression of the resistance genes. The increased growth rate in groundwater amended with glucose and phosphate had no significant influence on plasmid loss or antibiotic-resistance expression, suggesting that plasmid loss and antibiotic-resistance expression were independent of the growth rate. Most of the reduction of resistance gene expression was associated with the presence of soil particles, and 70% of the resistance expression was retained in bacteria incubated for 1 d in groundwater alone. Bacteria sorbed to the soil particles had a lower frequency of expression of resistance genes than suspended bacteria, but the difference was not caused by sorbed inorganic or organic chemicals. Resistance gene expression was partly recovered in suspended bacteria after in vitro exposure to the antibiotics and after first isolating on agar without antibiotics and then replica plating to agar containing the antibiotics.},
  author       = {Bengtsson, Göran and Fossum, A and Lindqvist, R},
  issn         = {1352-2310},
  language     = {eng},
  number       = {6},
  pages        = {999--1008},
  publisher    = {Elsevier},
  series       = {Atmospheric Environment},
  title        = {Persistence of plasmid RP4 in Pseudomonas putida and loss of its expression of antibiotic resistance in a groundwater microcosm},
  url          = {http://dx.doi.org/10.1016/j.soilbio.2004.02.015},
  volume       = {36},
  year         = {2004},
}