Dissemination of catabolic plasmids among desiccation-tolerant bacteria in soil microcosms |
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Authors: | Weekers Frederic Rodriguez Christian Jacques Philippe Mergeay Maximilien Thonart Philippe |
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Affiliation: | (1) Walloon Center for Industrial Biology, University of Liege, B40, 4000 Liege, Belgium;(2) Walloon Center for Industrial Biology, Agricultural University of Gembloux, Passage des Deportes, 2-5030 Gembloux, Belgium;(3) Belgian Nuclear Research Center, Boeretang 200, B-2400 Mol, Belgium |
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Abstract: | The dissemination of catabolic plasmids was compared to bioaugmentation by strain inoculation in microcosm experiments. When Rhodococcus erythropolis strain T902, bearing a plasmid with trich loroethene and isopropylbenzene degradation pathways, was used as the inoculum, no transconjugant was isolated but the strain remained in the soil. This plasmid had a narrow host range. Pseudomonas putida strain C8S3 was used as the inoculum in a second approach. It bore a broad host range conjugative plasmid harboring a natural transposon, RP4∶Tn4371, responsible for biphenyl and 4-chlorobiphenyl degradation pathways. The inoculating population slowly decreased from its original level (106 colony-forming units [CFU]/g of dry soil) to approx 3×102 CFU/g of dry soil after 3 wk. Transconjugant populations degrading biphenyl appeared in constant humidity soil (up to 2×103 CFU/g) and desiccating soil (up to 104 CFU/g). The feasibility of plasmid dissemination as a bioaugmentation technique was demonstrated in desiccating soils. The ecologic significance of desiccation in bioaugmentation was demonstrated; it upset the microbial ecology and the development of transconjugants. |
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Keywords: | Bioaugmentation drought tolerance conjugation plasmid dissemination microcosm isopropylbenzene |
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