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

Sutton NB, Atashgahi S, Saccenti E, Grotenhuis T, Smidt H, Rijnaarts HH - PLoS ONE (2015)

Bottom Line: In contrast, high permanganate treatment disrupted dechlorination beyond cis-dichloroethene and caused at least a 2-4 orders of magnitude reduction in the abundance of all measured OHRB and rdh genes, as compared to the biotic control.High permanganate treatments resulted in a notably divergent microbial community, with increased abundances of organisms affiliated with Campylobacterales and Oceanospirillales capable of dissimilatory Mn reduction, and decreased abundance of presumed supporters of OHRB.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.

View Article: PubMed Central - PubMed

Affiliation: Environmental Technology, Wageningen University, Wageningen, The Netherlands.

ABSTRACT
While in situ 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 (rdh) 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 rdh 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 Clostridiales and Deltaproteobacteria possibly supporting OHRB by providing essential co-factors. In contrast, high permanganate treatment disrupted dechlorination beyond cis-dichloroethene and caused at least a 2-4 orders of magnitude reduction in the abundance of all measured OHRB and rdh genes, as compared to the biotic control. High permanganate treatments resulted in a notably divergent microbial community, with increased abundances of organisms affiliated with Campylobacterales and Oceanospirillales capable of dissimilatory Mn reduction, and decreased abundance of presumed supporters of OHRB. Although OTUs classified within the OHR-supportive order Clostridiales 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.

No MeSH data available.


Molar percentage of chlorinated solvent PCE and degradation products TCE, cis-DCE, VC, and ethene and Mn2+.Results given for high (100 μmol) permanganate treatment, as described in Fig 1. (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.
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pone.0134615.g002: Molar percentage of chlorinated solvent PCE and degradation products TCE, cis-DCE, VC, and ethene and Mn2+.Results given for high (100 μmol) permanganate treatment, as described in Fig 1. (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.

Mentions: In contrast to the more mild permanganate treatments, significant disruption of OHR activity was observed in microcosms receiving high (100 μmol) permanganate doses (Fig 2). Following the first treatment on day 0, cis-DCE production in the high permanganate microcosms (93%; Fig 2) was similar to that of all other treatments (91–95%; Fig 1A–1C). However, following the second PCE spike on day 3, dehalogenation to cis-DCE required a week. Following a second permanganate treatment on day 13, dehalogenation was more significantly disrupted (Fig 2). Regeneration of PCE dechlorination coupled to TCE and cis-DCE accumulation resumed 4 days after the second permanganate addition on day 13. A third permanganate dose on day 33 severely disrupted OHR. Therefore, OHR activity was monitored over an extended period to determine if regeneration of PCE dechlorination could be observed. While some regeneration was measured on day 147 in H7, no dechlorination was observed in H8 and H9. Throughout the entire experiment, no VC or ethene production was observed at any point in microcosms receiving high permanganate treatments (Fig 2). Overall these results indicate that stronger chemical oxidant treatments can severely disrupt dechlorination.


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

Sutton NB, Atashgahi S, Saccenti E, Grotenhuis T, Smidt H, Rijnaarts HH - PLoS ONE (2015)

Molar percentage of chlorinated solvent PCE and degradation products TCE, cis-DCE, VC, and ethene and Mn2+.Results given for high (100 μmol) permanganate treatment, as described in Fig 1. (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.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526698&req=5

pone.0134615.g002: Molar percentage of chlorinated solvent PCE and degradation products TCE, cis-DCE, VC, and ethene and Mn2+.Results given for high (100 μmol) permanganate treatment, as described in Fig 1. (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.
Mentions: In contrast to the more mild permanganate treatments, significant disruption of OHR activity was observed in microcosms receiving high (100 μmol) permanganate doses (Fig 2). Following the first treatment on day 0, cis-DCE production in the high permanganate microcosms (93%; Fig 2) was similar to that of all other treatments (91–95%; Fig 1A–1C). However, following the second PCE spike on day 3, dehalogenation to cis-DCE required a week. Following a second permanganate treatment on day 13, dehalogenation was more significantly disrupted (Fig 2). Regeneration of PCE dechlorination coupled to TCE and cis-DCE accumulation resumed 4 days after the second permanganate addition on day 13. A third permanganate dose on day 33 severely disrupted OHR. Therefore, OHR activity was monitored over an extended period to determine if regeneration of PCE dechlorination could be observed. While some regeneration was measured on day 147 in H7, no dechlorination was observed in H8 and H9. Throughout the entire experiment, no VC or ethene production was observed at any point in microcosms receiving high permanganate treatments (Fig 2). Overall these results indicate that stronger chemical oxidant treatments can severely disrupt dechlorination.

Bottom Line: In contrast, high permanganate treatment disrupted dechlorination beyond cis-dichloroethene and caused at least a 2-4 orders of magnitude reduction in the abundance of all measured OHRB and rdh genes, as compared to the biotic control.High permanganate treatments resulted in a notably divergent microbial community, with increased abundances of organisms affiliated with Campylobacterales and Oceanospirillales capable of dissimilatory Mn reduction, and decreased abundance of presumed supporters of OHRB.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.

View Article: PubMed Central - PubMed

Affiliation: Environmental Technology, Wageningen University, Wageningen, The Netherlands.

ABSTRACT
While in situ 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 (rdh) 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 rdh 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 Clostridiales and Deltaproteobacteria possibly supporting OHRB by providing essential co-factors. In contrast, high permanganate treatment disrupted dechlorination beyond cis-dichloroethene and caused at least a 2-4 orders of magnitude reduction in the abundance of all measured OHRB and rdh genes, as compared to the biotic control. High permanganate treatments resulted in a notably divergent microbial community, with increased abundances of organisms affiliated with Campylobacterales and Oceanospirillales capable of dissimilatory Mn reduction, and decreased abundance of presumed supporters of OHRB. Although OTUs classified within the OHR-supportive order Clostridiales 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.

No MeSH data available.