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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.Results are given for (A) the biotic control, (B) low (25 μmol) permanganate treatment, and (C) medium (50 μmol) permanganate treatment. As the absolute mass increased over the course of the experiment due to PCE spiking (see Table 1), values are given as the molar percentage of all chlorinated compounds and ethene present at any time point. Headspace analysis of PCE, TCE, cis-DCE, VC, and ethene concentrations was always performed one day after each PCE spiking and nearly always in triplicate. the chemical analyses were shuffled between replicate microcosms of each treatment. Hence, the chemical results presented here are a conglomeration of chemical data from in total 9 microcosms.
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pone.0134615.g001: Molar percentage of chlorinated solvent PCE and degradation products TCE, cis-DCE, VC, and ethene.Results are given for (A) the biotic control, (B) low (25 μmol) permanganate treatment, and (C) medium (50 μmol) permanganate treatment. As the absolute mass increased over the course of the experiment due to PCE spiking (see Table 1), values are given as the molar percentage of all chlorinated compounds and ethene present at any time point. Headspace analysis of PCE, TCE, cis-DCE, VC, and ethene concentrations was always performed one day after each PCE spiking and nearly always in triplicate. the chemical analyses were shuffled between replicate microcosms of each treatment. Hence, the chemical results presented here are a conglomeration of chemical data from in total 9 microcosms.

Mentions: During six doses of permanganate (three cycles of two doses per cycle) over the course of 21 days, OHR was not severely interrupted in microcosms receiving low and medium permanganate treatments of 25 μmol or 50 μmol (Fig 1). Rather, VC production and dechlorination rates were higher in microcosms receiving mild permanganate treatments as compared to the biotic control (Fig 1). For example, on day 8 more than twice as much VC had been produced in microcosms receiving medium permanganate doses, as compared to the biotic control (80% VC versus 37% VC, respectively). In the biotic control, the 80% threshold was not crossed until day 14, a delay of over a week compared to the medium permanganate treatment (Fig 1). Similarly, higher final ethene production was observed in permanganate treated microcosms as compared to the biotic control (31% in medium microcosms versus 20% in the biotic control on day 21). Additionally, PCE and TCE degradation in the first day after spiking was higher in microcosms receiving low or medium permanganate treatments (S1 Fig). In the biotic control microcosms, residual PCE or TCE were often observed the day after a PCE spike (Table 1 and Fig 1), with PCE spiked on days 16 and 17 remaining in the system until the end of incubation on day 21 (Fig 1A). In contrast, in microcosms treated with medium permanganate doses complete conversion of spiked PCE to cis-DCE occurred within 1 day after spiking in nearly all instances (Fig 1C), yielding consistent degradation rates (S1C Fig). These results indicate that chemical oxidation does not disrupt OHR; rather, mild treatments appear to slightly stimulate 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.Results are given for (A) the biotic control, (B) low (25 μmol) permanganate treatment, and (C) medium (50 μmol) permanganate treatment. As the absolute mass increased over the course of the experiment due to PCE spiking (see Table 1), values are given as the molar percentage of all chlorinated compounds and ethene present at any time point. Headspace analysis of PCE, TCE, cis-DCE, VC, and ethene concentrations was always performed one day after each PCE spiking and nearly always in triplicate. the chemical analyses were shuffled between replicate microcosms of each treatment. Hence, the chemical results presented here are a conglomeration of chemical data from in total 9 microcosms.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134615.g001: Molar percentage of chlorinated solvent PCE and degradation products TCE, cis-DCE, VC, and ethene.Results are given for (A) the biotic control, (B) low (25 μmol) permanganate treatment, and (C) medium (50 μmol) permanganate treatment. As the absolute mass increased over the course of the experiment due to PCE spiking (see Table 1), values are given as the molar percentage of all chlorinated compounds and ethene present at any time point. Headspace analysis of PCE, TCE, cis-DCE, VC, and ethene concentrations was always performed one day after each PCE spiking and nearly always in triplicate. the chemical analyses were shuffled between replicate microcosms of each treatment. Hence, the chemical results presented here are a conglomeration of chemical data from in total 9 microcosms.
Mentions: During six doses of permanganate (three cycles of two doses per cycle) over the course of 21 days, OHR was not severely interrupted in microcosms receiving low and medium permanganate treatments of 25 μmol or 50 μmol (Fig 1). Rather, VC production and dechlorination rates were higher in microcosms receiving mild permanganate treatments as compared to the biotic control (Fig 1). For example, on day 8 more than twice as much VC had been produced in microcosms receiving medium permanganate doses, as compared to the biotic control (80% VC versus 37% VC, respectively). In the biotic control, the 80% threshold was not crossed until day 14, a delay of over a week compared to the medium permanganate treatment (Fig 1). Similarly, higher final ethene production was observed in permanganate treated microcosms as compared to the biotic control (31% in medium microcosms versus 20% in the biotic control on day 21). Additionally, PCE and TCE degradation in the first day after spiking was higher in microcosms receiving low or medium permanganate treatments (S1 Fig). In the biotic control microcosms, residual PCE or TCE were often observed the day after a PCE spike (Table 1 and Fig 1), with PCE spiked on days 16 and 17 remaining in the system until the end of incubation on day 21 (Fig 1A). In contrast, in microcosms treated with medium permanganate doses complete conversion of spiked PCE to cis-DCE occurred within 1 day after spiking in nearly all instances (Fig 1C), yielding consistent degradation rates (S1C Fig). These results indicate that chemical oxidation does not disrupt OHR; rather, mild treatments appear to slightly stimulate 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.