10 research outputs found

    Characterization of a Bisphenol A Specific Yeast Bioreporter Utilizing the Bisphenol A‑Targeted Receptor

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    The first <i>Saccharomyces cerevisiae</i> yeast bioreporter for analysis of a single endocrine disrupting compound, bisphenol A (BPA), was developed. The bioreporter contains mutated human estrogen receptor α (hERα), called bisphenol A-targeted receptor (BPA-R). The BPA-R bioreporter was characterized with mixtures of estrogenic chemicals and tested with spiked influent wastewater samples. The detection limit for BPA was 4.2-fold lower (0.107 μM, i.e., 24 μg L<sup>–1</sup>), while that of the native hormone 17β-estradiol (E2) (1 μM, i.e., 272 μg L<sup>–1</sup>) was 166,000-fold higher compared to the wild type hERα bioreporter. The BPA-R bioreporter responded only to BPA in a chemical cocktail and spiked concentrated wastewater samples with high concentrations of other estrogenic chemicals. As a conclusion, wastewater and other environmental water samples can be concentrated and specifically analyzed for BPA without risk of the mixture effect caused by other estrogenic chemicals. The BPA-R bioreporter is a robust and cost-efficient choice for high-throughput monitoring of BPA and its bioavailability in complex samples

    Comparison of Metals and Tetracycline as Selective Agents for Development of Tetracycline Resistant Bacterial Communities in Agricultural Soil

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    Environmental selection of antibiotic resistance may be caused by either antibiotic residues or coselecting agents. Using a strictly controlled experimental design, we compared the ability of metals (Cu or Zn) and tetracycline to (co)­select for tetracycline resistance in bacterial communities. Soil microcosms were established by amending agricultural soil with known levels of Cu, Zn, or tetracycline known to represent commonly used metals and antibiotics for pig farming. Soil bacterial growth dynamics and bacterial community-level tetracycline resistance were determined using the [<sup>3</sup>H]­leucine incorporation technique, whereas soil Cu, Zn, and tetracycline exposure were quantified by a panel of whole-cell bacterial bioreporters. Tetracycline resistance increased significantly in soils containing environmentally relevant levels of Cu (≥365 mg kg<sup>–1</sup>) and Zn (≥264 mg kg<sup>–1</sup>) but not in soil spiked with unrealistically high levels of tetracycline (up to 100 mg kg<sup>–1</sup>). These observations were consistent with bioreporter data showing that metals remained bioavailable, whereas tetracycline was only transiently bioavailable. Community-level tetracycline resistance was correlated to the initial toxicant-induced inhibition of bacterial growth. In conclusion, our study demonstrates that toxic metals in some cases may exert a stronger selection pressure for environmental selection of resistance to an antibiotic than the specific antibiotic itself

    Raw gene copy numbers detected in a WWTP sample (copy number/ml).

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    <p>A - 16S rRNA gene in inflow (IF) and effluent (EF). Assay1 was used only for samples from large WWTP (Helsinki) from Winter 2010 to Autumn 2011; B–Antibiotic resistance genes (ARGs). Statistical significance between inflow wastewater and effluent samples: *** - p<0.01; *0.03>p>0.01. For the pairs not marked the statistical difference between inflow and outflow was statistically insignificant. The line in each box marks the median and boxes: 25th and 75th percentiles; whiskers: 5th and 95th percentiles and outliers ±1.5 * IQR. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0103705#pone.0103705.s001" target="_blank">Figure S2 in File S1</a> for abundances of same genes presented by each sampling event.</p

    Sampling sites and their descriptions.

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    a<p>Mean values of depth, temperature (T) and pH were measured from bottom seawater at sampling sites located in the archipelago area in the northern Baltic Sea.</p

    Correlation analysis.

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    <p>Linear regression model with log-transformed variables between the <i>intI1</i> and <i>sul1</i> gene copy numbers in the sediments below the northern Baltic Sea farms (<i>F<sub>1,22</sub></i> = 19.39; <i>P</i> = 0.000225; <i>R<sup>2</sup></i> = 0.47). Each point represents the average ratio of a gene copy number normalized to the 16S rRNA gene copy number in every sediment sample. The blue line indicates the regression model and the grey area the 95% confidence intervals.</p

    Development of Highly Sensitive, Automatized and Portable Whole-Cell Hg Biosensor Based on Environmentally Relevant Microorganisms

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    <p>Whole-cell biosensors are still the method of choice when measuring bioavailable mercury, though their implementation in environmental monitoring is limited by low sensitivity, lack of portability and use of environmentally irrelevant bacteria. To address these issues, we have engineered a new luminescence-based whole-cell mercury biosensor, as part of a standalone fully automated portable device. Our method allows the incorporation of any environmentally relevant bacterial cell, which has been modified to translate the concentration of biologically available mercury into a dose-dependent luminescent signal. The use of environmentally relevant bacteria, <i>Pseudomonas putida</i> for fresh waters and <i>Aliivibrio fischeri</i> for salt waters, demonstrated that environmental samples will not exhibit toxic effects, when appropriate microorganisms are implemented. Additionally, by assuring efficient aeration of the medium and thus sufficient oxygenation of sensor cells during generation of the luminescence signal, we obtained a clear dose-dependent response and observed an increased sensitivity of the method up to 100 times (the limit of detection [LOD] was determined to be as low as ∼10 ng L<sup>−1</sup>). Finally, using our automated device, we demonstrated that in the environment the biologically available fraction of mercury can (1) represent an important part of the total mercury content (40–70%) and (2) it can correspond to the changes of total mercury content, which results in higher bioavailability of mercury closer to the source of mercury contamination.</p