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Development of bioreporter assays for the detection of bioavailability of long-chain alkanes based on the marine bacterium Alcanivorax borkumensis strain SK2

Authors

  • Rekha Kumari,

    1. Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
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    • Present addresses: Department of Zoology, Miranda House, University of Delhi, Delhi, India;

  • Robin Tecon,

    1. Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
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    • Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, the Netherlands.

  • Siham Beggah,

    1. Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
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  • Rebecca Rutler,

    1. Environmental Chemistry Modeling Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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  • J. Samuel Arey,

    1. Environmental Chemistry Modeling Laboratory, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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  • Jan Roelof van der Meer

    Corresponding author
    1. Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
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E-mail janroelof.vandermeer@unil.ch; Tel. (+41) 41 21 692 5630; Fax (+41) 21 692 5605.

Summary

Long-chain alkanes are a major component of crude oil and therefore potentially good indicators of hydrocarbon spills. Here we present a set of new bacterial bioreporters and assays that allow to detect long-chain alkanes. These reporters are based on the regulatory protein AlkS and the alkB1 promoter from Alcanivorax borkumensis SK2, a widespread alkane degrader in marine habitats. Escherichia coli cells with the reporter construct reacted strongly to octane in short-term (6 h) aqueous suspension assays but very slightly only to tetradecane, in line with what is expected from its low water solubility. In contrast, long-term assays (up to 5 days) with A. borkumensis bioreporters showed strong induction with tetradecane and crude oil. Gel-immobilized A. borkumensis reporter cells were used to demonstrate tetradecane and crude oil bioavailability at a distance from a source. Alcanivorax borkumensis bioreporters induced fivefold more rapid and more strongly when allowed physical contact with the oil phase in standing flask assays, suggesting a major contribution of adhered cells to the overall reporter signal. Using the flask assays we further demonstrated the effect of oleophilic nutrients and biosurfactants on oil availability and degradation by A. borkumensis. The fluorescence signal from flask assays could easily be captured with a normal digital camera, making such tests feasible to be carried out on, e.g. marine oil responder vessels in case of oil accidents.

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