Bioreactive Barriers:  A Comparison of Bioaugmentation and Biostimulation for Chlorinated Solvent Remediation

Lendvay, John; Löffler, Frank E.; Dollhopf, M.; Aiello, Michael R.; Daniels, Gary; Fathepure, Babu Z.; Gebhard, M.; Heine, R.; Helton, Rebekah R.; Shi, J.; Krajmalnik‐Brown, Rosa; Major, C. L.; Barcelona, Michael J.; Petrovskis, Erik; Hickey, Robert F.; Tiedje, James M.; Adriaens, Peter

doi:10.1021/es025985u

Cited by 276 publications

(229 citation statements)

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“…Several microbial groups carry out respiratory reductive dechlorination 1 , but one genus, Dehalococcoides, seems particularly adapted to a unique niche, and the bacteria are only known to use chloroorganics as electron acceptors and hydrogen as an electron donor for growth. Several studies have now shown successful application of Dehalococcoides-containing cultures for in situ remediation of contaminated sites 2,3 . The recently described genome sequence of D. ethenogenes, strain 195 (ref.…”

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Genome sequence of the chlorinated compound–respiring bacterium Dehalococcoides species strain CBDB1

et al. 2005

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Dehalococcoides species are strictly anaerobic bacteria, which catabolize many of the most toxic and persistent chlorinated aromatics and aliphatics by reductive dechlorination and are used for in situ bioremediation of contaminated sites. Our sequencing of the complete 1,395,502 base pair genome of Dehalococcoides strain CBDB1 has revealed the presence of 32 reductive-dehalogenase-homologous (rdh) genes, possibly conferring on the bacteria an immense dehalogenating potential. Most rdh genes were associated with genes encoding transcription regulators such as two-component regulatory systems or transcription regulators of the MarR-type. Four new paralog groups of rdh-associated genes without known function were detected. Comparison with the recently sequenced genome of Dehalococcoides ethenogenes strain 195 reveals a high degree of gene context conservation (synteny) but exceptionally high plasticity in all regions containing rdh genes, suggesting that these regions are under intense evolutionary pressure.In the past century, human activities have released large amounts of chlorinated organic compounds into the environment, and these compounds are among the most pervasive groundwater pollutants. Chloroorganics with fewer chlorines can usually be biodegraded by aerobic microorganisms, whereas more highly chlorinated ones can be reductively dechlorinated by organisms using them as electron acceptors for anaerobic respiration. Several microbial groups carry out respiratory reductive dechlorination 1 , but one genus, Dehalococcoides, seems particularly adapted to a unique niche, and the bacteria are only known to use chloroorganics as electron acceptors and hydrogen as an electron donor for growth. Several studies have now shown successful application of Dehalococcoides-containing cultures for in situ remediation of contaminated sites 2,3 . The recently described genome sequence of D. ethenogenes, strain 195 (ref. 4), an organism that reductively dechlorinates the solvents tetrachloroethene and trichloroethene to vinyl chloride and ethene 5 , reflects this specialization: although only 1.47-megabases (Mb) long, the genome possesses 17 rdhAB pairs potentially encoding reductive dehalogenases and genes predicted to encode five different hydrogenase complexes. We describe here the genome sequence of Dehalococcoides sp. strain CBDB1, a bacterium that has in many ways a different dechlorination spectrum from strain 195. For instance, strain CBDB1 (refs. 6,7) dechlorinated 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 2,3-dichloro-p-dibenzodioxin and the 'Seveso dioxin ' 2,3,7,8-tetrachloro-p-dibenzodioxin, but strain 195 (ref. 8) did not. In contrast to strain 195, strain CBDB1 did not dechlorinate tetrachloroethene past dichloroethene 6 . By sequencing a second Dehalococcoides genome, we can now show that strain CBDB1 has an even greater potential as a reductive dechlorinator than strain 195 and, in addition, the comparison of the two genomes with each other provides insights into the evolution of reductive dechlori...

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Genome sequence of the chlorinated compound–respiring bacterium Dehalococcoides species strain CBDB1

et al. 2005

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“…Amplification efficiency, standard curve slope, r 2 value, y-intercept, C T determination method, are more rarely reported, however, a recent study provided a summary of many of these parameters . Detection limits are more frequently reported, some examples for soil, sediment or liquid samples are as follows: 10 2 copies per g of aquifer material (Lendvay et al, 2003); 120 copies per g of soil (Sleep et al, 2006); ∼ 10 3 copies per L of groundwater (Rahm et al, 2006b); 100 to 1000 copies per L of groundwater ; and 500 copies per L bench-scale aquifer effluent (Sleep et al, 2006).…”

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confidence: 99%

“…to in situ bioremediation (Adamson et al, 2003;Ellis et al, 2000;Hendrickson et al, 2002;Lendvay et al, 2003;Lu et al, 2006;Major et al, 2002;Nijenhuis et al, 2007;Rahm et al, 2006b). Initial investigations involved the addition of mixed cultures containing Dehalococcoides spp.…”

Section: Contribution To Bioremediation Effortsmentioning

confidence: 99%

“…Initial investigations involved the addition of mixed cultures containing Dehalococcoides spp. to promote complete in situ dechlorination to ethene (Ellis et al, 2000;Major et al, 2002), and later, Dehalococcoides targeted qPCR was incorporated into assessment procedures to evaluate bioaugmentation efficacy (Lendvay et al, 2003;Rahm et al, 2006b). For example, qPCR targeting Dehalococcoides spp.…”

Section: Contribution To Bioremediation Effortsmentioning

confidence: 99%

“…For example, qPCR targeting Dehalococcoides spp. has been used to compare bioaugmentation to biostimulation for chlorinated solvent remediation (Lendvay et al, 2003). The authors found the bioaugmented plot contained at least an order of magnitude greater Dehalococcoides cell numbers compared to the biostimulated plot.…”

Section: Contribution To Bioremediation Effortsmentioning

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Methods and Applications

Arveson

2002

Graduate Texts in Mathematics

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Dehalococcoides species are responsible for the reductive dehalogenation of an impressive range of common, persistent environmental contaminants. These microorganisms are difficult to both obtain and grow in pure culture, and so are often studied while they exist in consortia using molecular techniques. In particular, a significant number of quantitative real-time PCR (qPCR) assays targeting Dehalococcoides spp. have been reported. Initial qPCR methods targeted the 16S rRNA gene, however, because strains with the same 16S rRNA gene sequence can have different dehalogenating abilities, reductive dehalogenase genes are now emerging as the most appropriate qPCR target. Quantitative PCR has been critical to our current understanding of Dehalococcoides populations; it has provided information on their growth characteristics, dehalogenating abilities and effective use in bioremediation efforts. Future qPCR research directions will likely involve method standardization, as well as continued research on the functional genes associated with Dehalococcoides populations.

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Chlorinated Hydrocarbon Metabolism

Reineke¹,

Mandt²,

Kaschabek³

et al. 2011

Encyclopedia of Life Sciences

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The widespread global distribution of chlorinated hydrocarbons, their high lipophilicity and their recalcitrance have contributed to their importance as environmental toxicants. Their metabolism under oxic and anoxic conditions mediated by prokaryotic and eukaryotic cells is discussed. Various aerobic bacteria are able to use chlorinated hydrocarbons as the sole source of carbon and energy and some anaerobic bacteria can use some of these as an artificial electron acceptor in reductive dechlorination. Liver enzymes are responsible for the formation of hydrophilic metabolites ready for excretion which often lead to highly reactive and potentially toxic intermediates. Whereas fungi, especially ligninolytic ones, usually only exhibit ‘side activities’ for chlorinated hydrocarbons. The capabilities of bacteria had led to the development of various bioremediation processes. Both, successes and failures within these processes are known. Therefore, current research aims at a better understanding of global community interactions. Key Concepts: Chlorinated hydrocarbons have been produced by the chemical industry since nearly a decade in large amounts, but they can also be observed as natural compounds, sometimes exceeding the industrially produced amounts. Even though toxicological properties have pushed the chlorochemistry into the focus of considerable debate and governmental regulatory action, chlorinated hydrocarbons remain essential for certain applications. The aerobic metabolism of chlorinated hydrocarbons by bacteria has been studied in detail and an immense amount of information is available on pathways, enzymes and genes involved in the mineralisation of chloroaromatics. The anaerobic degradation of chlorinated hydrocarbons is due to the capablity of anaerobic bacteria to use them in anaerobic respiration, which results in dechlorination. Dehalococcoides organisms are the most versatile reductive dehalogenators as being capable to dehalogenate chlorinated dioxins, biphenyls, benzenes and vinyl chloride, among others. Microbial activities have been widespread used for bioremediation purposes through natural attenuation, biostimulation and bioaugmentation. The poor understanding of the functioning of the complex microbial activities in situ made bioremediation efforts quite unreliable. The rapid development of molecular techniques in recent years allows immense insights into the processes in situ , but also on the overall physiology of biocatalysts.

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Bioreactive Barriers: A Comparison of Bioaugmentation and Biostimulation for Chlorinated Solvent Remediation

Cited by 276 publications

References 23 publications

Genome sequence of the chlorinated compound–respiring bacterium Dehalococcoides species strain CBDB1

Genome sequence of the chlorinated compound–respiring bacterium Dehalococcoides species strain CBDB1

Methods and Applications

Chlorinated Hydrocarbon Metabolism

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