Molar percentage of chlorinated solvent PCE and degradation products TCE, <i>cis</i>-DCE, VC, and ethene and Mn²⁺.

<p>Results given for high (100 μmol) permanganate treatment, as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134615#pone.0134615.g001" target="_blank">Fig 1</a>. (A) Days 1–33, during which the most PCE spiking and degradation occurred, are given in more detail. (B and C) Results from extended incubation period including Mn²⁺ concentrations. Results are split for H7 (B) and H8+H9 (C) to show difference in regeneration in degradation between these microcosms.</p

Redundancy Analysis Triplot showing relationship between microbial community composition at order level and treatments.

<p>Treatment variables are given as open arrows and are described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134615#pone.0134615.t002" target="_blank">Table 2</a>. Closed arrows represent orders. Orders were included with a relative abundance of at least 0.05 in any sample. Arrow length gives the variance that can be explained by a particular treatment parameter. Perpendicular distance reflects association, with smaller distances indicating a larger association. H7, H8 and H9 are left out of this plot because the long incubation times skew the scales, thus compressing the rest of the plot. A Triplot with all samples in this study is given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134615#pone.0134615.s003" target="_blank">S3 Fig</a>.</p

Heatmap of 10 most abundant OTUs in data set.

<p>Sample labels as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134615#pone.0134615.t002" target="_blank">Table 2</a> and relative abundances are given as fraction of 1.</p

Microbial Community Response of an Organohalide Respiring Enrichment Culture to Permanganate Oxidation

<div><p>While <i>in situ</i> chemical oxidation is often used to remediate tetrachloroethene (PCE) contaminated locations, very little is known about its influence on microbial composition and organohalide respiration (OHR) activity. Here, we investigate the impact of oxidation with permanganate on OHR rates, the abundance of organohalide respiring bacteria (OHRB) and reductive dehalogenase (<i>rdh</i>) genes using quantitative PCR, and microbial community composition through sequencing of 16S rRNA genes. A PCE degrading enrichment was repeatedly treated with low (25 μmol), medium (50 μmol), or high (100 μmol) permanganate doses, or no oxidant treatment (biotic control). Low and medium treatments led to higher OHR rates and enrichment of several OHRB and <i>rdh</i> genes, as compared to the biotic control. Improved degradation rates can be attributed to enrichment of (1) OHRB able to also utilize Mn oxides as a terminal electron acceptor and (2) non-dechlorinating community members of the <i>Clostridiales</i> and <i>Deltaproteobacteria</i> possibly supporting OHRB by providing essential co-factors. In contrast, high permanganate treatment disrupted dechlorination beyond <i>cis</i>-dichloroethene and caused at least a 2–4 orders of magnitude reduction in the abundance of all measured OHRB and <i>rdh</i> genes, as compared to the biotic control. High permanganate treatments resulted in a notably divergent microbial community, with increased abundances of organisms affiliated with <i>Campylobacterales</i> and <i>Oceanospirillales</i> capable of dissimilatory Mn reduction, and decreased abundance of presumed supporters of OHRB. Although OTUs classified within the OHR-supportive order <i>Clostridiales</i> and OHRB increased in abundance over the course of 213 days following the final 100 μmol permanganate treatment, only limited regeneration of PCE dechlorination was observed in one of three microcosms, suggesting strong chemical oxidation treatments can irreversibly disrupt OHR. Overall, this detailed investigation into dose-dependent changes of microbial composition and activity due to permanganate treatment provides insight into the mechanisms of OHR stimulation or disruption upon chemical oxidation.</p></div

Summary of treatments and timing.

<p>Samples were taken at start of experiment (“S”), and during treatment as biotic control (“B”), and receiving low (“L”), medium (“M”), or high (“H”) permanganate doses. Treatment times, cumulative permanganate (PM) and number of permanganate doses are used as model inputs for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134615#pone.0134615.t003" target="_blank">Table 3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134615#pone.0134615.g006" target="_blank">Fig 6</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134615#pone.0134615.s003" target="_blank">S3 Fig</a>. Number of sequences and operational taxonomic units (OTUs) obtained for each sample are given.</p

Relative target abundance of OHRB (based on 16S rRNA gene) and <i>rdh</i> genes measured by qPCR.

<p>Values indicate the enrichment or reduction of a target relative to that measured in the biotic control. Data is averaged between duplicate microcosms for each time point prior to comparison with the biotic control. Error bars are the propagation of standard deviation in triplicate assays, averaging of duplicates, and calculation of relative abundance. (A) Results in low or medium permanganate treated microcosms are compared to results from the biotic control at the same time point. (B) Results from the high permanganate microcosms were compared to the biotic control on day 13 (H1+H2) and day 21 (H3+H4, H5+H6). H7, H8, and H9 are not included, as biotic controls are not available for these time points. Note that different concentration scales are used for Y axes of (A) and (B) panels.</p

Association between treatment variables and microbial community composition at order level.

<p>Treatment variables are from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0134615#pone.0134615.t002" target="_blank">Table 2</a>. Orders were included with relative abundances above 0.05 in any sample. Significant associations are given in bold (<i>P</i>-value < 0.01).</p

Metabolism of Ibuprofen by <i>Phragmites australis</i>: Uptake and Phytodegradation

This study explores ibuprofen (IBP) uptake and transformation in the wetland plant species <i>Phragmites australis</i> and the underlying mechanisms. We grew <i>P. australis</i> in perlite under greenhouse conditions and treated plants with 60 μg/L of IBP. Roots and rhizomes (RR), stems and leaves (SL), and liquid samples were collected during 21 days of exposure. Results show that <i>P. australis</i> can take up, translocate, and degrade IBP. IBP was completely removed from the liquid medium after 21 days with a half-life of 2.1 days. IBP accumulated in RR and was partly translocated to SL. Meanwhile, four intermediates were detected in the plant tissues: hydroxy-IBP, 1,2-dihydroxy-IBP, carboxy-IBP and glucopyranosyloxy-hydroxy-IBP. Cytochrome P450 monooxygenase was involved in the production of the two hydroxy intermediates. We hypothesize that transformation of IBP was first catalyzed by P450, and then by glycosyltransferase, followed by further storage or metabolism in vacuoles or cell walls. No significant phytotoxicity was observed based on relative growth of plants and stress enzyme activities. In conclusion, we demonstrated for the first time that <i>P. australis</i> degrades IBP from water and is therefore a suitable species for application in constructed wetlands to clean wastewater effluents containing IBP and possibly also other micropollutants

Geochemical and Microbiological Characteristics during in Situ Chemical Oxidation and in Situ Bioremediation at a Diesel Contaminated Site

While in situ chemical oxidation with persulfate has seen wide commercial application, investigations into the impacts on groundwater characteristics, microbial communities and soil structure are limited. To better understand the interactions of persulfate with the subsurface and to determine the compatibility with further bioremediation, a pilot scale treatment at a diesel-contaminated location was performed consisting of two persulfate injection events followed by a single nutrient amendment. Groundwater parameters measured throughout the 225 day experiment showed a significant decrease in pH and an increase in dissolved diesel and organic carbon within the treatment area. Molecular analysis of the microbial community size (16S rRNA gene) and alkane degradation capacity (<i>alkB</i> gene) by qPCR indicated a significant, yet temporary impact; while gene copy numbers initially decreased 1–2 orders of magnitude, they returned to baseline levels within 3 months of the first injection for both targets. Analysis of soil samples with sequential extraction showed irreversible oxidation of metal sulfides, thereby changing subsurface mineralogy and potentially mobilizing Fe, Cu, Pb, and Zn. Together, these results give insight into persulfate application in terms of risks and effective coupling with bioremediation