COBIOT-861; NO. OF PAGES 7
Available online at www.sciencedirect.com
Sequential anaerobic/aerobic biodegradation
of chloroethenes—aspects of field application
Andreas Tiehm and Kathrin R Schmidt
Because of a range of different industrial activities, sites
contaminated with chloroethenes are a world-wide problem.
Chloroethenes can be biodegraded by reductive dechlorination
under anaerobic conditions as well as by oxidation under
aerobic conditions. The tendency of chloroethenes to undergo
reductive dechlorination decreases with a decreasing number
of chlorine substituents, whereas with less chlorine
substituents chloroethenes more easily undergo oxidative
degradation. There is currently a growing interest in aerobic
metabolic degradation of chloroethenes, which demonstrates
advantages compared to cometabolic degradation pathways.
Sequential anaerobic/aerobic biodegradation can overcome
the disadvantages of reductive dechlorination and leads to
complete mineralization of the chlorinated pollutants. This
approach shows promise for site remediation in natural settings
and in engineered systems.
Address
Department of Environmental Biotechnology, Water Technology Center,
Karlsruher Straße 84, 76139 Karlsruhe, Germany
Corresponding author: Tiehm, Andreas ([email protected])
Current Opinion in Biotechnology 2011, 22:1–7
This review comes from a themed issue on
Environmental biotechnology
Edited by Lindsay Eltis and Ariel Kushmaro
0958-1669/$ – see front matter
# 2011 Elsevier Ltd. All rights reserved.
DOI 10.1016/j.copbio.2011.02.003
Introduction
Because of diverse industrial activities, sites contaminated with man-made chemicals are a world-wide problem [1]. Halogenated solvents, especially chloroethenes,
are among the most prevalent pollutants in contaminated
aquifers [2,3]. At many polluted sites, engineered bioremediation and natural attenuation (NA) processes are
considered as possibilities for site remediation since
microbiological approaches often require less intervention and are less expensive than physical or chemical
remediation measures [4–7].
In the past decades many researchers have focused on
anaerobic reductive dechlorination, which transforms
the primary contaminants perchloroethene (PCE)
and trichloroethene (TCE) to cis-1,2-dichloroethene
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(cDCE), vinyl chloride (VC) and ethene. A thorough
understanding of halorespiration, also named organohalide respiration, was obtained [1,4,7–12]. During the
same period of time aerobic metabolic degradation of
VC was extensively studied [13,14,15,16]. In recent
years, new aerobic metabolic cDCE degrading processes
were reported [3,17,18,19,20,21,22]. Aerobic cometabolic biodegradation represents another remediation
approach but requires large amounts of auxiliary substrates [23–25].
It is the objective of this review (i) to summarize current
knowledge of bacterial degradation of chloroethenes, (ii)
to compare aerobic metabolic with aerobic cometabolic
degradation and (iii) to discuss the advantages and drawbacks of field remediation approaches based on anaerobic
reductive dechlorination and sequential anaerobic/aerobic biodegradation.
Microbial degradation of chloroethenes
Depending on the degree of chlorination of the ethene
molecule and on the prevailing site conditions biodegradation can occur via reductive dechlorination as well as via
oxidative degradation. Reductive dechlorination only
takes place under anaerobic conditions. The tendency
of chloroethenes to undergo reductive dechlorination
decreases as numbers of chlorine substituents decrease.
Conversely, chloroethenes more easily undergo oxidative
degradation with decreasing numbers of chlorine substituents (Figure 1) [26].
Oxidation of chloroethenes is known to happen under
aerobic conditions [21,22,26]. Anaerobic oxidation has
been described in laboratory studies [4] but knowledge
still remains scarce [12]. It was recently postulated that
anaerobic oxidation observed in the field might in truth
be aerobic oxidation with very low amounts of oxygen
[15].
Anaerobic reductive dechlorination
Anaerobic reductive dechlorination or halorespiration has
already been extensively investigated and reviewed
[1,4,7–12]. Reductive dechlorination is an anaerobic
respiration process, using chloroethenes as electron
acceptors and hydrogen as electron donor. In engineered
bioremediation, hydrogen is typically made available by
the addition of organic carbon. The auxiliary substrates
added in the field are converted to hydrogen by fermentative bacteria present in the autochthonous microbial
community. The hydrogen atoms replace the chlorine
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COBIOT-861; NO. OF PAGES 7
2 Environmental biotechnology
Figure 1
anaerobic-reductive
aerobic-oxidative
decreasing with fewer chloroatoms
increasing with fewer chloroatoms
Cl
auxiliary
substrates
Cl
PCE
C=C
Cl
reduced organic
carbon
H2
Cloxidized organic
carbon
Cl
CO2
H
C=C
TCE
Cl
Cl
H
H
ClcDCE
C=C
Cl
Cl
H
H
H2O
VC
C=C
H
Cl
H
H
auxiliary
substrates
ethene
C=C
H
oxidation of
auxiliary substrates
(electron donors)
Cl
only needed for
cometabolism
O2
H
reduction of
chloroethenes
(electron acceptors)
oxidation of
chloroethenes
(electron donors)
reduction of
oxygen
(electron acceptor)
Current Opinion in Biotechnology
Overview of chloroethene biodegradation (PCE: perchloroethene; TCE: trichloroethene; cDCE: cis-1,2-dichloroethene; and VC: vinyl chloride).
atoms one after the other resulting in the typical dechlorination sequence from PCE, via TCE, cDCE and VC
down to ethene (Figure 1). Formation of the other
dichloroethenes trans-1,2-dichloroethene (tDCE) and
1,1-dichloroethene (1,1-DCE) is possible but rarely
observed.
The rate of reductive dechlorination decreases with
decreasing numbers of chloroatoms. Several groups of
bacteria such as Desulfomonile, Dehalobacter, Desulfitobacterium and Desulfuromonas are known to be able to degrade
PCE via TCE to the end product cDCE. However, only
bacteria of the Dehalococcoides group are capable of performing the complete reductive dechlorination from PCE
to ethene [1,26]. Also for Dehalococcoides, the dechlorination of PCE to cDCE is faster and thermodynamically
more favourable than the dechlorination from cDCE to
VC. The slowest dechlorination step is the final transformation of VC to ethene [1,4,12]. Therefore, an
accumulation of cDCE or VC is often observed at contaminated sites [27,28].
Anaerobic reductive dechlorination is widely applied for
site remediation, often with the dosage of electron donors
as auxiliary substrates (biostimulation) [2] or dosage of
microorganisms specialized for reductive dechlorination
(bioaugmentation) [6]. Stable carbon isotope fractionation
can be used for proof and quantification of anaerobic
reductive dechlorination in the field [28]. Molecular
biology methods are available for the detection of halorespiring bacteria, providing a useful tool for fast and easy
Current Opinion in Biotechnology 2011, 22:1–7
determination of the site-specific degradation potential
[6,7,27,29].
Aerobic oxidative degradation
Under aerobic conditions, chloroethenes can be oxidized
both cometabolically and metabolically. During cometabolic degradation the chloroethenes are only degraded
fortuitously. The degrading enzymes are actually produced for the degradation of bacterial growth substrates
(named auxiliary substrates) like methane, ethene,
ammonium or aromatic pollutants [23–25,26]. Cometabolic degradation has been shown for all chloroethenes
[14,24,25,30–35]. Cometabolic degradation of PCE was
rarely described, with the latest publication in the year
2000 [35]. It was recently stated that PCE is not degraded
by methanotrophs [36].
On the contrary, metabolic degradation denotes the use of
a chloroethene as a growth substrate [26]. Metabolic
degradation has so far been repeatedly shown for cDCE
and VC [3,13,14,15,16,17,18,19,20,21,22]. For tDCE
only one report about metabolic degradation was found
[18]. Furthermore, VC can serve as an auxiliary substrate
for the cometabolic degradation of cDCE [14]. Very
recent results show that interactions between different
chloroethenes during aerobic metabolic degradation of a
chloroethene within a mixture have to be taken into
account [22].
With regard to site remediation applications, aerobic
metabolic degradation offers several advantages over
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Sequential anaerobic/aerobic biodegradation of chloroethenes—aspects of field application Tiehm and Schmidt 3
Figure 2
anaerobic conditions
reductive dechlorination
aerobic conditions
cometabolic oxidation
metabolic oxidation
electron donors / auxiliary substrates
reduced organic carbon / NH4+
H2
NO3-
O2
O2
N2
CH4
CO2
II Mn(IV)
Mn(II)
NH4+
NO3-
III Fe(III)
Fe(II)
…
IV
TCE, cDCE,
VC, ethene
I
PCE
SO42HCO3
S2-
HCO3-
VC
cDCE
TCE
(PCE)
CO2
ClH2O
VC
cDCE
CO2
ClH2O
CH4
CH3COOH
reduction of chloroethenes
and competing TEAs
oxidation of chloroethenes
and electron donors
oxidation of chloroethenes
Current Opinion in Biotechnology
Comparison of reductive dechlorination with cometabolic and metabolic oxidation in terms of need for auxiliary substrates as electron donors and
competing reactions (PCE: perchloroethene; TCE: trichloroethene; cDCE: cis-1,2-dichloroethene; VC: vinyl chloride; and TEA: terminal electron
acceptor). The numbers indicate the order of the different respiration processes [5].
aerobic cometabolic degradation (Figure 2, middle and
right part). First of all, metabolic degradation does not
need any auxiliary substrates. Therefore competition
between auxiliary substrates and chloroethenes at the
degrading enzyme [24,25,26,30,37] as well as oxygen
consumption by the auxiliary substrates [3,21,22]
are avoided. There is no need for co-occurrence of contaminants, auxiliary substrates and oxygen within the
plume [21]. Groundwater quality is not impaired by
oxidation products of auxiliary substrates such as nitrate
[24]. Furthermore, for metabolic degradation complete
mineralization/assimilation of the organic molecules without intermediary toxic effects is assumed [26]. In consequence, product toxicity by cometabolic degradation
products such as epoxides or aldehydes leading to inactivation of the degrading enzymes and cell death
[3,24,30,31,35] seems not to be a problem during metabolic degradation. In addition, metabolic conversion proceeds at higher degradation rates [24] and displays higher
concentration ranges than cometabolic degradation [38].
The use of aerobic degradation processes for site remediation is described in the literature, but is less common
than the use of reductive dechlorination. Cometabolic
degradation has been applied in the field for degradation
of TCE, 1,1-DCE, tDCE, cDCE and VC [2,36,38–40].
Demonstration as well as application of metabolic degradation in the field appears to be rarer and has so far been
reported for cDCE and VC [27,41]. Aerobic degradation
can be accompanied by significant stable carbon isotope
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fractionation [14,21], which can be used for proof and
quantification of aerobic chloroethene biodegradation in
the field [27,40]. The development of molecular biology
methods for the detection of aerobic degraders is currently underway [26,28,36,42].
Environmental pre-requisites and impacts of
reductive dechlorination
Anaerobic site conditions and electron donors are needed
for reductive dechlorination to take place. In an aerobic
aquifer electron donors are first needed to remove competing electron acceptors such as oxygen and nitrate in
order to achieve anaerobic conditions [36]. Even when
strongly anaerobic conditions are obtained, the halorespiring bacteria still compete for electron donors with other
hydrogenotrophs such as sulphate-reducers, methanogens and acetogens (Figure 2, left part) [1,43]. It was
observed in the laboratory that reductive dechlorination
was slowed in the presence of sulphate reduction [44]. At
field sites, nitrate reduction, manganese(IV) reduction,
iron(III) reduction and sulphate reduction as well as
methanogenesis occurred during stimulation of reductive
dechlorination [2,45].
As a consequence of this competition reductive dechlorination consumes only a small percentage of the available
electrons [43,44] resulting in the wastage of reducing
equivalents/auxiliary substrates [46,47]. This is of great
importance for site remediation since electron donors
cause significant costs during field application [44].
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4 Environmental biotechnology
Furthermore, bioclogging can be a problem due to the
dosage of high amounts of electron donors [46,47].
cesses in situ (enhanced natural attenuation, ENA) or in
engineered systems.
Moreover, strongly reducing conditions can lead to the
accumulation of harmful products such as hydrogen sulphide and methane [44]. Excess methane formation can
even pose an explosion hazard [46,47]. Additionally,
reducing conditions can lead to the solubilization of toxic
metals in their reduced form [36,44]. These unwanted
side-products can be detrimental to groundwater quality
and can increase groundwater ecotoxicity [47].
At a PCE/TCE contaminated site in Germany sequential
anaerobic/aerobic degradation was found to occur naturally. PCE and TCE are anaerobically reduced to mainly
cDCE; reductive dechlorination to VC is restricted to a
small anaerobic zone in the plume. Both metabolites are
then oxidized metabolically [21,27]. This site-specific
degradation scheme was established based on multiple
lines of evidence. Corresponding results were obtained
from pollutant profiles, redox conditions, characterization
of the autochthonous microflora, degradation studies in
laboratory microcosms and the assessment of stable carbon
isotope fractionation [27]. These assessment methods were
reviewed by Tiehm and Schmidt [5]. A related approach
was applied by Abe et al. [28], who demonstrated the
potential of VC oxidation at a field site in Canada where
reductive dechlorination of PCE occurs as a first step.
Until now, only bacteria from the Dehalococcoides genus
are known for complete reductive dechlorination [1,26].
These bacteria are restricted to anaerobic conditions [29]
and are very sensitive to oxygen [37]. Because of their
high degree of specialization in terms of usable electron
donors and acceptors [7] and their complex nutritional
requirements [1,29] they can only thrive under certain
environmental conditions and are less versatile and less
robust than other halorespiring bacteria [7].
If the environmental conditions are not strictly reducing
and therefore not suitable for growth of Dehalococcoides,
other dechlorinating bacteria can transform PCE to cDCE
resulting in the formation of a cDCE-contaminated
plume [27,28]. Even in the presence of Dehalococcoides,
unfavourable conditions can stall the halorespiration process following the formation of the carcinogenic VC
[1,12,48]. Furthermore, ethene is considered a suspected
carcinogen [49,50]. Thus, even the often-intended complete reductive dechlorination to ethene would not result
in transformation of chloroethenes into completely innocuous products.
Application of sequential anaerobic/aerobic
biodegradation
According to current knowledge, biodegradation of PCE
can only be accomplished with a first anaerobic dechlorination step. However, reductive dechlorination often
tends to stall at cDCE/VC [27,28]. Aerobic – especially
metabolic – degradation provides a way to entirely mineralize the pollutants [3,26]. Aerobic degradation of
cDCE even supersedes the reductive step from cDCE
to VC, which is especially useful since reductive dechlorination often stalls at cDCE [2]. Thus, the use of aerobic
degradation for complete biodegradation via a sequential
anaerobic/aerobic approach is superior to the use of complete reductive dechlorination for field sites lacking naturally strong reducing conditions. In the case of TCE
contamination, aerobic cometabolic degradation can be
a useful approach, as it requires no anaerobic degradation
step [36].
So far, few publications are available describing the
natural occurrence of sequential anaerobic/aerobic degradation in the field (NA) or the stimulation of such proCurrent Opinion in Biotechnology 2011, 22:1–7
Sequential stimulation of anaerobic/aerobic biodegradation was applied in pilot tests [51,52]. Electron donors and
nutrients were injected into the aquifer in order to create
an anaerobic zone, followed by biosparging in order to
create an aerobic zone. However, when considering the
injection of oxygen into an anaerobic aquifer, precipitation of ferric iron and clogging of groundwater wells
must be taken into account [53]. At another field site
sequential anaerobic/aerobic biodegradation was stimulated unintentionally. Long years of reductive dechlorination stimulation led to strong methanogenesis, which
in turn enabled aerobic cometabolic methanotrophic
TCE degradation [2].
Different bioreactor designs were developed in order to
achieve sequential stimulation of anaerobic/aerobic biodegradation in laboratory studies. Sequential systems
with separate reactors for reductive dechlorination and
for aerobic degradation were set up [23,43,54,55]. Other
bioreactors were designed to allow anaerobic as well as
aerobic biodegradation in a single stage reactor with
biofilms containing methanogenic/methanotrophic consortia with a steep oxygen gradient across the biofilm
[37,56]. Electron donors were provided by dosage of
organic substrates or by formation of hydrogen through
water electrolysis [43]. Oxygen was delivered by dosage
of oxygen releasing compounds, air or through water
electrolysis [43,57].
Conclusion
Biodegradation of chloroethenes has been demonstrated
to be a technically viable and cost-effective method for
site remediation. Microbiological elimination of chloroethenes can be achieved by complete reductive dechlorination or by sequential anaerobic/aerobic treatment
(Figure 3). Complete reductive dechlorination of PCE
via TCE, cDCE and VC to ethene is possible under
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Sequential anaerobic/aerobic biodegradation of chloroethenes—aspects of field application Tiehm and Schmidt 5
Figure 3
industrial
site
(a)
unsaturated
zone
source areas
groundwater
flow direction
ane
meth
PCE
TCE
cDCE
uncontaminated
oxidized groundwater
H2 S
VC
aquifer
saturated
zone
contaminated
reduced groundwater
aquitard
industrial
site
(b)
unsaturated
zone
source areas
groundwater
flow direction
PCE
TCE
uncontaminated
oxidized groundwater
cDCE
VC
CO2
Cl-
aquifer
saturated
zone
H2O
uncontaminated
oxidised groundwater
aquitard
Current Opinion in Biotechnology
Schematic view on pollutant distribution and hydrochemical site characteristics following a chloroethene spill (PCE: perchloroethene; TCE:
trichloroethene; cDCE: cis-1,2-dichloroethene; and VC: vinyl chloride). Scenario a shows excess electron donor availability and incomplete reductive
dechlorination. This scenario results in accumulation of cDCE and VC and anaerobic side reactions such as sulphate reduction and methanogenesis
leaving a strongly reducing aquifer behind. Scenario b shows moderate electron donor availability and sequential anaerobic/aerobic biodegradation.
This scenario results in complete mineralization of the pollutants and an aerobic aquifer left behind.
strictly anaerobic conditions. However, this approach
risks the accumulation of cDCE or VC (Figure 3, a). In
order to stimulate complete reductive dechlorination at
polluted sites, electron donors, that is organic compounds
or hydrogen, are injected in excess resulting in competing
processes such as sulphate reduction and methanogenesis
occurring simultaneously (Figure 3, a). On the contrary, in
recent years aerobic metabolic degradation of cDCE and
VC has been demonstrated. In contrast to the previously
known aerobic cometabolic degradation processes in the
presence of auxiliary substrates such as ammonium or
methane, metabolic biodegradation does not require the
addition of other electron donors. Therefore, the recently
discovered metabolic aerobic processes in particular have
a strong potential for field application (Figure 3, b).
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During the development of bioremediation concepts,
site-specific microbial community and hydrochemical
conditions must be taken into consideration. In aquifers
with strictly anaerobic conditions, complete reductive
dechlorination might be the most favourable approach.
At contaminated sites with less reducing conditions a
sequential anaerobic/aerobic approach is encouraged for
field application (Figure 3, b).
The main advantages of the sequential anaerobic/aerobic
approach are (i) the prevention of accumulation of toxic
stable metabolites, (ii) no need for highly sensitive bacteria of the Dehalococcoides genus and (iii) less need for
electron donors as auxiliary substrates. Furthermore,
aeration following stimulation of reductive dechlorination
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COBIOT-861; NO. OF PAGES 7
6 Environmental biotechnology
will result in higher groundwater quality than after reductive dechlorination alone (Figure 3, b).
16. Jin YO, Cheung S, Coleman NV, Mattes TE: Association of
missense mutations in epoxyalkane coenzyme M transferase
with adaptation of Mycobacterium sp. strain JS623 to growth
on vinyl chloride. Appl Environ Microbiol 2010, 76:3413-3419.
Acknowledgements
17. Mattes TE, Alexander AK, Richardson PM, Munk AC, Han CS,
Stothard P, Coleman NV: The genome of Polaromonas sp. strain
JS666: insights into the evolution of a hydrocarbon- and
xenobiotic-degrading bacterium, and features of relevance to
biotechnology. Appl Environ Microbiol 2008, 74:6405-6416.
The authors gratefully acknowledge financial support by the German
Ministry of Education and Research (BMBF; grant no. 02WA1052) and the
Israeli Ministry of Science, Culture and Sport (MOST). The authors are
responsible for the content of this publication. We thank Ian Marshall for
proof-reading the manuscript.
References and recommended reading
Papers of particular interest, published within the period of review,
have been highlighted as:
of special interest
of outstanding interest
1.
Futagami T, Goto M, Furukawa K: Biochemical and genetic
bases of dehalorespiration. Chem Rec 2008, 8:1-12.
2.
Conrad ME, Brodie EL, Radtke CW, Bill M, Delwiche ME, Lee MH,
Swift DL, Colwell FS: Field evidence for co-metabolism of
trichloroethene stimulated by addition of electron donor to
groundwater. Environ Sci Technol 2010, 44:4697-4704.
Description of a very interesting field case.
3.
Giddings CGS, Liu F, Gossett JM: Microcosm assessment of
Polaromonas sp. JS666 as a bioaugmentation agent for
degradation of cis-1,2-dichloroethene in aerobic, subsurface
environments. Ground Water Monit Remediation 2010,
30:106-113.
Interesting report about the usefulness of aerobic metabolic degradation
of cis-1,2-dichloroethene for remediation practice.
4.
Bradley PM: History and ecology of chloroethene
biodegradation: a review. Bioremediat J 2003, 7:81-109.
5.
Tiehm A, Schmidt KR: Methods to evaluate biodegradation at
contaminated sites. In Environmental Geology—Handbook of
Field Methods and Case Studies. Edited by Knödel K, Lange G,
Voigt H-J. Springer-Verlag; 2007:876-911.
6.
7.
Vainberg S, Condee CW, Steffan RJ: Large-scale production of
bacterial consortia for remediation of chlorinated solventcontaminated groundwater. J Ind Microbiol Biotechnol 2009,
36:1189-1197.
Maphosa F, de Vos WM, Smidt H: Exploiting the ecogenomics
toolbox for environmental diagnostics of organohaliderespiring bacteria. Trends Biotechnol 2010, 28:308-316.
8.
El Fantroussi S, Naveau H, Agathos SN: Anaerobic
dechlorinating bacteria. Biotechnol Prog 1998, 14:167-188.
9.
Fetzner S: Bacterial dehalogenation. Appl Microbiol Biotechnol
1998, 50:633-657.
10. Smidt H, Akkermans ADL, van der Oost J, de Vos WM:
Halorespiring bacteria-molecular characterization and
detection. Enzyme Microb Technol 2000, 27:812-820.
11. van Pée K-H, Unversucht S: Biological dehalogenation and
halogenation reactions. Chemosphere 2003, 52:299-312.
12. Smidt H, de Vos WM: Anaerobic microbial dehalogenation.
Annu Rev Microbiol 2004, 58:43-73.
13. Jin YO, Mattes TE: Adaptation of aerobic, ethene-assimilating
Mycobacterium strains to vinyl chloride as a growth substrate.
Environ Sci Technol 2008, 42:4784-4789.
14. Tiehm A, Schmidt KR, Pfeifer B, Heidinger M: Growth kinetics
and stable carbon isotope fractionation during aerobic
degradation of cis-1,2-dichloroethene and vinyl chloride.
Water Res 2008, 42:2431-2438.
15. Gossett JM: Sustained aerobic oxidation of vinyl chloride
at low oxygen concentrations. Environ Sci Technol 2010,
44:1405-1411.
Important contribution about the possibility of aerobic oxidation of vinyl
chloride in aquifers containing low amounts of oxygen.
Current Opinion in Biotechnology 2011, 22:1–7
18. Olaniran AO, Pillay D, Pillay B: Aerobic biodegradation of
dichloroethenes by indigenous bacteria isolated from
contaminated sites in Africa. Chemosphere 2008, 73:24-29.
Sole report found about aerobic metabolic degradation of trans-1,2dichloroethene.
19. Abe Y, Aravena R, Zopfi J, Shouakar-Stash O, Cox E, Roberts JD,
Hunkeler D: Carbon and chlorine isotope fractionation during
aerobic oxidation and reductive dechlorination of vinyl
chloride and cis-1,2-dichloroethene. Environ Sci Technol 2009,
43:101-107.
20. Jennings LK, Chartrand MMG, Lacrampe-Couloume G, Sherwood
Lollar B, Spain JC, Gossett JM: Proteomic and transcriptomic
analyses reveal genes upregulated by cis-dichloroethene in
Polaromonas sp. strain JS666. Appl Environ Microbiol 2009,
75:3733-3744.
21. Schmidt KR, Augenstein T, Heidinger M, Ertl S, Tiehm A:
Metabolic aerobic biodegradation of cis-1,2-dichloroethene:
Stable carbon isotope fractionation and growth
characteristics. Chemosphere 2010, 78:527-532.
Interesting results about reproducible stable carbon isotope fractionation
during metabolic aerobic cis-1,2-dichloroethene degradation under different incubation conditions; growth characteristics in a mineral medium
without ammonium.
22. Zhao HP, Schmidt KR, Tiehm A: Inhibition of aerobic metabolic
cis-1,2-di-chloroethene biodegradation by other
chloroethenes. Water Res 2010, 44:2276-2282.
Gives important indications about possible inhibiting effects between
chloroethenes during aerobic degradation of chloroethene mixtures.
23. Tiehm A, Gozan M, Müller A, Schell H, Lorbeer H, Werner P:
Sequential anaerobic/aerobic biodegradation of chlorinated
hydrocarbons in activated carbon barriers. Water Sci Technol
2002, 2:51-58.
24. Sayavedra-Soto LA, Gvakharia B, Bottomley PJ, Arp DJ,
Dolan ME: Nitrification and degradation of halogenated
hydrocarbons—a tenuous balance for ammonia-oxidizing
bacteria. Appl Microbiol Biotechnol 2010, 86:435-444.
25. Wendlandt K-D, Stottmeister U, Helm J, Soltmann B, Jechorek M,
Beck M: The potential of methane-oxidizing bacteria for
applications in environmental biotechnology. Eng Life Sci 2010,
10:87-102.
26. Mattes TE, Alexander AK, Coleman NV: Aerobic biodegradation
of the chloroethenes: pathways, enzymes, ecology, and
evolution. FEMS Microbiol Rev 2010, 34:445-475.
Extensive review on aerobic oxidation of chloroethenes focussing on
metabolic degradation of vinyl chloride.
27. Schmidt KR, Tiehm A: Natural attenuation of chloroethenes:
identification of sequential reductive/oxidative
biodegradation by microcosm studies. Water Sci Technol 2008,
58:1137-1145.
28. Abe Y, Aravena R, Zopfi J, Parker B, Hunkeler D: Evaluating the
fate of chlorinated ethenes in streambed sediments by
combining isotope, geochemical and microbial methods. J
Contam Hydrol 2009, 107:10-21.
29. Cupples AM: Real-time PCR quantification of Dehalococcoides
populations: methods and applications. J Microbiol Methods
2008, 72:1-11.
30. Frascari D, Pinelli D, Nocentini M, Baleani E, Cappelletti M, Fedi S:
A kinetic study of chlorinated solvent cometabolic
biodegradation by propane-grown Rhodococcus sp. PB1.
Biochem Eng J 2008, 42:139-147.
31. Doughty DM, Sayavedra-Soto LA, Arp DJ, Bottomley PJ: Effects
of dichloroethene isomers on the induction and activity of
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Sequential anaerobic/aerobic biodegradation of chloroethenes—aspects of field application Tiehm and Schmidt 7
butane monooxygenase in the alkane-oxidizing bacterium
‘‘Pseudomonas butanovora’’. Appl Environ Microbiol 2005,
71:6054-6059.
44. Aulenta F, Beccari M, Majone M, Papini MP, Tandoi V:
Competition for H2 between sulfate reduction and
dechlorination in butyrate-fed anaerobic cultures. Process
Biochem 2008, 43:161-168.
32. Semprini L, Dolan ME, Hopkins GD, McCarty PL:
Bioaugmentation with butane-utilizing microorganisms to
promote in situ cometabolic treatment of 1,1,1trichloroethane and 1,1-dichloroethene. J Contam Hydrol 2009,
103:157-167.
45. Bennett P, Gandhi D, Warner S, Bussey J: In situ reductive
dechlorination of chlorinated ethenes in high nitrate
groundwater. J Hazard Mater 2007, 149:568-573.
33. Chen Y-M, Lin T-F, Huang C, Lin J-C: Cometabolic degradation
kinetics of TCE and phenol by Pseudomonas putida.
Chemosphere 2008, 72:1671-1680.
46. Heimann AC, Friis AK, Scheutz C, Jakobsen R: Dynamics of
reductive TCE dechlorination in two distinct H2 supply
scenarios and at various temperatures. Biodegradation 2007,
18:167-179.
34. Kim S, Bae W, Hwang J, Park J: Aerobic TCE degradation by
encapsulated toluene-oxidizing bacteria Pseudomonas
putida and Bacillus spp.. Water Sci Technol 2010, 62:1991-1997.
35. Ryoo D, Shim H, Canada K, Barbieri P, Wood TK: Aerobic
degradation of tetrachloroethylene by toluene-o-xylene
monooxygenase of Pseudomonas stutzeri OX1. Nat Biotechnol
2000, 18:775-777.
36. Hazen TC, Chakraborty R, Fleming JM, Gregory IR, Bowman JP,
Jimenez L, Zhang D, Pfiffner SM, Brockman FJ, Sayler GS: Use of
gene probes to assess the impact and effectiveness of aerobic
in situ bioremediation of TCE. Arch Microbiol 2009, 191:221-232.
37. Guiot SR, Cimpoia R, Kuhn R, Alaplantive A: Electrolytic
methanogenic-methanotrophic coupling for
tetrachloroethylene bioremediation: proof of concept. Environ
Sci Technol 2008, 42:3011-3017.
38. Goltz MN, Gandhi RK, Gorelick SM, Hopkins GD, Smith LH,
Timmins BH, McCarty PL: Field evaluation of in situ source
reduction of trichloroethylene in groundwater using
bioenhanced in-well vapor stripping. Environ Sci Technol 2005,
29:8963-8970.
39. Hopkins GD, McCarty PL: Field evaluation of in situ aerobic
cometabolism of trichloroethylene and three dichloroethylene
isomers using phenol and toluene as the primary substrates.
Environ Sci Technol 1995, 29:1628-1637.
40. Pooley KE, Blessing M, Schmidt TC, Haderlein SB, Macquarrie KB,
Prommer H: Aerobic biodegradation of chlorinated ethenes in
a fractured bedrock aquifer: quantitative assessment by
compound-specific isotope analysis (CSIA) and reactive
transport modeling. Environ Sci Technol 2009, 43:7458-7464.
47. Aulenta F, Pera A, Rossetti S, Petrangeli Papini M, Majone M:
Relevance of side reactions in anaerobic reductive
dechlorination microcosms amended with different electron
donors. Water Res 2007, 41:27-38.
48. Kielhorn J, Melber C, Wahnschaffe U, Aitio A, Mangelsdorf I: Vinyl
chloride: still a cause for concern. Environ Health Persp 2000,
108:579-588.
49. Törnqvist M: Is ambient ethene a cancer risk factor? Environ
Health Persp 1994, 102:157-160.
50. Bolt HM: The carcinogenic risk of ethene (ethylene). Toxicol
Pathol 1998, 26:454-456.
51. Devlin JF, Katic D, Barker JF: In situ sequenced bioremediation
of mixed contaminants in groundwater. J Contam Hydrol 2004,
69:233-261.
52. Noell AL: Estimation of sequential degradation rate
coefficients for chlorinated ethenes. Pract Periodical Hazard
Toxic Radioactive Waste Manage 2009, 13:35-44.
53. Tiehm A, Müller A, Alt S, Jacob H, Schad H, Weingran C:
Development of a groundwater biobarrier for the
removal of polycyclic aromatic hydrocarbons, BTEX,
and heterocyclic hydrocarbons. Water Sci Technol 2008,
58:1349-1355.
54. Gerritse J, Kloetstra G, Borger A, Dalstra G, Alphenaar A,
Gottschal JC: Complete degradation of tetrachloroethene in
coupled anoxic and oxic chemostats. Appl Microbiol Biotechnol
1997, 48:553-562.
41. Davis GB, Patterson BM, Johnston CD: Aerobic bioremediation
of 1,2 dichloroethane and vinyl chloride at field scale. J Contam
Hydrol 2009, 107:91-100.
55. Kao CM, Chen SC, Wang JY, Chen YL, Lee SZ: Remediation of
PCE-contaminated aquifer by an in situ two-layer biobarrier:
laboratory batch and column studies. Biodegradation 2003,
37:27-38.
42. Giddings CGS, Jennings LK, Gossett JM: Microcosm
assessment of a DNA probe applied to aerobic degradation of
cis-1,2-dichloroethene by Polaromonas sp. strain JS666.
Ground Water Monit Remediation 2010, 30:97-105.
56. Tartakovsky B, Manuel M-F, Guiot SR: Trichloroethylene
degradation in a coupled anaerobic/aerobic reactor
oxygenated using hydrogen peroxide. Environ Sci Technol
2003, 27:5823-5828.
43. Lohner ST, Tiehm A: Application of electrolysis to stimulate
microbial reductive PCE dechlorination and oxidative VC
biodegradation. Environ Sci Technol 2009, 43:7098-7104.
57. Tiehm A, Lohner ST, Augenstein T: Effects of direct electric
current and electrode reactions on vinyl chloride degrading
microorganisms. Electrochim Acta 2009, 54:3453-3459.
www.sciencedirect.com
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