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Microbial characterization of artificial sediment and comparisons with natural sediments—implication for toxicity testing

Authors

  • Willem Goedkoop,

    Corresponding author
    1. Department of Environmental Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-750 07 Uppsala, Sweden
    • Department of Environmental Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-750 07 Uppsala, Sweden
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  • Anneli Widenfalk,

    1. Department of Environmental Assessment, Swedish University of Agricultural Sciences, Box 7050, SE-750 07 Uppsala, Sweden
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  • Ann-Louise Haglund,

    1. Department of Public Technology, Mälardalen University, Box 883, SE-721 23 Västerås, Sweden
    2. Limnology/Department of Ecology and Evolution, Uppsala University, Norbyvägen 20, SE-752 36, Uppsala, Sweden
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  • Kristin Steger,

    1. Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, SE-750 07 Uppsala, Sweden
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  • Stefan Bertilsson

    1. Limnology/Department of Ecology and Evolution, Uppsala University, Norbyvägen 20, SE-752 36, Uppsala, Sweden
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Abstract

The development and activity of microbiota in artificial sediment may have strong implications for the fate of test compounds and the outcome of toxicity tests. In this study, we compare a number of microbial variables in the artificial sediment commonly used in toxicity testing with that of natural sediments. Bacterial abundance of artificial sediment ranged 5.7 to 7.1 × 108 cells/g wet weight, which is about two orders of magnitude lower than values commonly reported for natural sediments. Similarly, alternative estimates of microbial biomass (sum of phospholipid fatty acid, ergosterol, adenosine triphosphate) were several times lower for artificial sediment compared with natural sediment. Bacterial activity (3H-thymidine incorporation) ranged 4.0 to 7.4 pmol g−1 h−1 (or 0.062–0.113 μg C g−1 h−1) in artificial sediments, which is low compared with values commonly reported for freshwater sediments. Community respiration in artificial sediment was 34 to 93 μg CO2 g−1 d−1. Bacterial community composition assessed by terminal restriction fragment length polymorphism of polymerase chain reaction amplified 16S rRNA genes demonstrated that natural bacterial communities appear to be more diverse than their counterparts in artificial sediment. The average similarity of the microbial communities obtained by this method was less than 40%, and different operational taxonomic units appeared to dominate the artificial and natural sediment, respectively. These results and supporting data from previous studies in natural sediments suggest that the artificial sediment has a poorly developed microbial component that differs substantially from that in natural sediments.

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