1. Environ. Sci. Technol. 2009, 43, 6553–6559
marine sediments or released from marine fossil reservoirs
Effect of Environmental Conditions (7, 8). Thus far, the highest AOM rates have been reported
on Sulfate Reduction with Methane for Hydrate Ridge and Black Sea sediments, 2-8 µmol
gdry weight-1 day-1 (9) and 8-21 µmol gdry weight-1 day-1 (10),
as Electron Donor by an Eckernforde
¨ respectively. AOM in marine sediments is mediated by
uncultured archaea, called anaerobic methanotrophs (ANME),
Bay Enrichment distantly related to cultivated methanogenic members from
the orders Methanosarcinales and Methanomicrobiales
R O E L J . W . M E U L E P A S , * ,†,‡ (11, 12). Thus far, three groups of ANME have been
CHRISTIAN G. JAGERSMA,§ distinguished, of which ANME-1 and ANME-2 are the most
AHMAD F. KHADEM,| common. ANME often live in consortia with sulfate-reducing
CEES J. N. BUISMAN,† bacteria (SRB) (13-15). It is likely that the ANME produces
ALFONS J. M. STAMS,§ AND an electron carrier compound from CH4 that is subsequently
P I E T N . L . L E N S †,‡ utilized by a sulfate-reducing partner (16, 5, 17, 18), although
Sub-department of Environmental Technology, Wageningen the exact pathway remains unclear.
University, Bomenweg 2, 6703 HD Wageningen, The In Vitro Studies. In vitro studies have demonstrated the
Netherlands, UNESCO-IHE, Environmental Resources, Westvest 7, coupling between AOM and SR according to conversion 1 (Table
2611 AX Delft, The Netherlands, Laboratory of Microbiology, 1) (19) and have shown that the exponential increase in AOM
Wageningen University, Dreijenplein 10, 6703 HB activity is coupled to growth of ANME/SRB consortia (20).
Wageningen, The Netherlands, and Department of Reported doubling times vary from 2 to 7 months (20-23).
Microbiology, Radboud University Nijmegen, Toernooiveld 1, Nauhaus et al. (24) and Treude et al. (25) investigated the effect
6525 ED Nijmegen, The Netherlands of temperature on SR by Hydrate Ridge, Black Sea and
Eckernforde Bay sediment, the optimal temperatures are
¨
Received March 2, 2009. Revised manuscript received June respectively: 16 °C or lower, around 20 °C, and between 20 and
29, 2009. Accepted July 7, 2009. 28 °C. AOM is sensitive to the methane partial pressure, and
unlike sulfate, Mn (IV), Fe (III), S°, and fumarate are not used
as electron acceptors for AOM by Hydrate Ridge sediment (24).
Application of Sulfate Reduction with Methane as
Sulfate reduction (SR) coupled to anaerobic oxidation of Electron Donor. Sulfate reduction with other electron donors
methane (AOM) is meditated by marine microorganisms and than CH4, like hydrogen, ethanol, and acetate, is well understood
forms an important process in the global sulfur and carbon cycle. (26, 27) and is an established biotechnological process (28-30).
In this research, the possibility to use this process for the Biological sulfate reduction can prevent the emission of toxic
removal and recovery of sulfur and metal compounds from waste metals and oxidized sulfur compounds that would acidify the
streams was investigated. A membrane bioreactor was used environment. Dissolved metals can be removed by precipitation
with biologically produced sulfide, the formed poorly soluble
to enrich for a community of methane-oxidizing sulfate-reducing
metal sulfides can be separated from the water and reused in
microorganisms from Eckernfo ¨rde Bay sediment. The AOM the metallurgical industry (28). Oxidized sulfur compounds can
and SR rate of the obtained enrichment were 1.0 mmol gVSS-1 be converted to the insoluble and reusable elemental sulfur by
d-1. The operational window and optimal environmental subsequently applying biological sulfate reduction and partial
conditions for SR with methane as electron donor were sulfide oxidation (31). Wastewaters rich in oxidized sulfur
assessed. The optimum pH, salinity, and temperature were compounds are produced in flue gas desulfurization and in
7.5, 30‰ and 20 °C, respectively. The enrichment had a good industries that use sulfuric acid or sulfate-rich feedstock, e.g.,
affinity for sulfate (Km < 0.5 mM) and a low affinity for methane fermentation or sea food processing industry (32). Waste waters
(Km > 0.075 MPa). AOM coupled to SR was completely of the mining (acid mine drainage) and the metallurgical
inhibited at 2.4 ((0.1) mM sulfide. AOM occurred with sulfate, industry contain both sulfur and metal compounds. However,
the costs of the electron donor limit the application of biological
thiosulfate, and sulfite as electron acceptors. Sulfate reduction
sulfate reduction. Of the conventional electron donors, hy-
with methane as electron donor can be applied for the removal
drogen is the most attractive for large-scale applications (33).
of sulfate or for the production of sulfide, for metal precipitation. Hydrogen is commonly derived from CH4 by steam reforming
However, the low optimal temperature and the high salt natural gas. Natural gas is 2-4 times cheaper than hydrogen
requirement limit the operational window of the process. per amount needed for sulfate reduction (34). The operation
costs of the treatment plant will thus be significantly reduced
Introduction if CH4 could be fed directly to sulfate-reducing bioreactors.
Sulfate Reduction with Methane as Electron Donor in Current Research. To assess the potential of CH4 as electron
Marine Sediments. Anaerobic oxidation of methane (AOM) donor for biological sulfate reduction in industrial applications,
occurs in marine sediments and is coupled to sulfate ANME were enriched in a membrane bioreactor (23), the
reduction (SR) (1-6), according to conversion 1 (Table 1). obtained CH4-oxidizing sulfate-reducing enrichment had an
AOM coupled to SR contributes largely to the removal of the activity of 1.0 mmol gVSS-1 d-1. In this research, the operational
greenhouse gas methane (CH4), produced in anaerobic window for AOM coupled to SR by this enrichment was assessed.
The effects of the temperature, pH, salinity, CH4 partial pressure,
* Corresponding author phone: +31 15 2151880; fax: +31 sulfate concentration, dissolved inorganic carbon concentra-
152122921; e-mail: r.meulepas@unesco-ihe.org. tion, and sulfide concentration, on the AOM and SR rate of the
†
Sub-department of Environmental Technology, Wageningen
CH4-oxidizing sulfate-reducing enrichment were investigated.
University.
‡
Environmental Resources, UNESCO-IHE. Additionally, alternative electron acceptors were tested. AOM
§
Laboratory of Microbiology, Wageningen University. was quantified from the production of 13C-labeled CO2 and
|
Department of Microbiology, Radboud University. 13
C-labeled HCO3- (∑13CO2) during incubation with 13C-labeled
10.1021/es900633c CCC: $40.75  2009 American Chemical Society VOL. 43, NO. 17, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 6553
Published on Web 07/28/2009

2. TABLE 1. Reduction and Disproportionation Conversions of Oxidized Sulfur Compounds and Their Standard Gibbs Free Energy
Changes at pH 7.0 (∆G°′)a
conversion stoichiometry ∆G°′
1 2- -
CH4 + SO4 f HCO3 + HS- + H2O -16.6 kJ mol-1 CH4
2 2- -
CH4 + S2O3 f HCO3 + 2 HS- + H+ -39 kJ mol-1 CH4
3 2- -
CH4 + 4/3 SO3 + 1/3 H+ f HCO3 + 4/3 HS- + H2O -95 kJ mol-1 CH4
4 -
CH4 + 4 S° + 3 H2O f HCO3 + 4 HS- + 5 H+ +24 kJ mol-1 CH4
5 -
CH4 + 8/5 NO3 + 8/5 H+ f CO2 + 4/5 N2 + 14/5H2O -765 kJ mol-1 CH4
6 4 SO3 + H+ f 3 SO4 + HS-
2- 2-
-236 kJ mol-1 SO32-
7 S2O3 + H2O f SO4 + HS- + H+
2- 2-
-22 kJ mol-1 S2O32-
8 4 S° + 4 H2O f SO4 + 3 HS- + 5 H+
2-
+40 kJ mol-1 S°
a
Gibbs free energy changes were obtained from ref 46.
FIGURE 1. Effect of temperature (A), pH (B), and salinity (C) on the AOM (b) and sulfide production (×) by the Eckernfo
¨rde Bay enrichment.
The bottles contained initially 0.13((01) MPa 13CH4 as sole energy and carbon source, 19((1) mM sulfate as sole electron acceptor and
less than 0.2 mM ∑CO2 and sulfide. The standard temperature, pH, and salinity were 15 °C, 7.4, and 30‰, respectively.
CH4 (13CH4). Labeled methane was used to prevent an over- Experiments were done in batch, in serum bottles of 35 mL
estimation of the AOM rate due endogenous carbon dioxide closed with butyl rubber stoppers and caps. After determination
production. of the exact weight and volume, the bottles were flushed eight
times with nitrogen gas and evacuated. Subsequently 28 mL of
Materials and Methods medium and 2 mL from the biomass stock were transferred to
Eckernforde Bay Enrichment. The biomass used for this
¨ the bottles by syringe. The headspace was made vacuum again
research was taken from a 1 L submerged-membrane biore- and filled 0.15 MPa 13C-labeled CH4 (13CH4) with a purity of
actor, used to enrich anaerobic methanotrophs. The reactor 99% from Campro (Veenendaal, The Netherlands). The bottles
was inoculated with 8.4 gdry weight sediment from Eckernforde
¨ were incubated and shaken at 15 °C, unless stated otherwise.
Bay (Baltic Sea) and fed with sulfate as electron acceptor and The gas composition, the pH, the pressure, and the liquid and
CH4 as electron donor and carbon source. During these 884 gas volume were measured once a week. Liquid samples were
days, the volumetric methane oxidation rate increased expo- taken ones every two weeks and used for sulfide and sulfate
nentially from 0.002 to 0.6 mmol L-1 day-1 (23). Molecular analyses, after filtering through a 0.2 µm cellulose acetate
analyses of the reactor suspension (mixture of liquid and membrane filter (Schleicher & Schuell OE 66, Schleicher &
suspended solids in the bioreactor) revealed that ANME became Schuell, Dassel, Germany).
the dominant archaea (23). Samples of the reactor suspension Experimental Setup. To assess the effect of temperature,
for the assessment of the effect of CH4, sulfate, and inorganic pH and salinity on the conversion rate of the CH4-oxidizing
carbon were taken on day 884 of the bioreactor run; reactor sulfate-reducing enrichment, incubations were done at 10, 15,
suspension samples for the other experiments were taken 20, 25, and 30 °C; a pH of 6.0, 6.5, 7.0, 7.5, 8.0, and 8.5; and a
between days 420 and 450. To ensure homogeneous sampling, salinity of 5, 10, 20, 30, 40, and 50‰. To obtain these conditions,
liquid recirculation (0.5 L min-1) and gas sparging (2 L min-1) the following modifications were done to the basal medium
were applied prior to and during sampling. A biomass stock and the standard incubation procedure. The pH was altered by
was made by collecting the reactor suspension in a bottle filled adding NaOH or HCl solution (1.0 M) to the individual bottles
with nitrogen gas. After the solids were allowed to settle, the until the final pH was reached. The salinity was varied by mixing
liquid could be removed with syringe and needle. In this way, medium from which all salts, other than magnesium sulfate,
the biomass was concentrated 15 times and washed 2 times were omitted with medium with a salinity of 50‰.
with fresh medium. To assess the effect of CH4, sulfate and total dissolved
Standard Incubations Procedure. The preparation pro- inorganic carbon (∑CO2) concentrations, incubations with
cedure and the composition of the basal medium are described different CH4 partial pressures (from 0.00 to 0.15 MPa), sulfate
by Meulepas et al. (23). Unless stated otherwise, the medium concentrations (0.5, 2, 5, 10, and 20 mM) and ∑CO2 concentra-
was buffered at pH 7.4 and the salinity (weight promillage of tions (0.5, 2, 10, and 25 mM) were done. To obtain the different
all dissolved salts) and sulfate concentration of the medium CH4 partial pressures, nitrogen and 13CH4 gas were sequentially
were 30‰ and 21 mM, respectively. added from pressurized bottles. The sulfate concentration was
6554 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 17, 2009

3. FIGURE 2. Effect of the CH4 partial pressure (A), sulfate concentration (B) and dissolved ∑CO2 (C) on the AOM (b), sulfide production
(×) and sulfate removal (0) by the Eckernforde Bay enrichment with 13CH4 as sole energy and carbon source and sulfate as sole
¨
electron acceptor. If not varied, the CH4 partial pressure and sulfate concentration were initially 0.13((0.01) MPa and 19((1) mM,
respectively. Both the initial ∑CO2 and sulfide concentration were less than 0.2 mM.
adjusted by adding sulfate from a stock solution (1.0 M) to ment were observed at all tested temperatures (10-30 °C),
sulfate-free medium. To obtain the different ∑CO2 concentra- at a pH from 6.5 to 9.0 and at a salinity from 10 to 50‰
tions, HCO3- (from a 1 M stock) and CO2 (from a pressurized (Figure 1). At a pH of 6.0 and a salinity of 4‰, no AOM or
bottle) were added. The amount of gas added could be SR were observed. The conversion was highest at a tem-
controlled by a reduction valve. perature of 20 °C, a pH of 7.5, and a salinity of 30‰. The
To assess the effect of sulfide, sulfide was allowed to incubations to determine the effect of temperature were done
accumulate in two bottles with standard medium and 0.15 MPa at optimal pH and salinity, but the incubations to determine
13
CH4. After the accumulation stopped, the sulfide was removed the effect of pH and salinity were done at suboptimal
by flushing the bottle with CH4 gas. Subsequently, the bottles temperature (15 °C). Therefore, the maximum rates in graph
were filled with 13CH4, incubated and regularly analyzed again B and C are lower than in graph A.
to test whether the inhibition was reversible. Effect of the Methane, Sulfate, ∑CO2, and Sulfide. Figure
Nitrate (10 mM), sulfur (0.5 mg L-1), sulfite (10 mM) and 2 presents the AOM and SR rates, of the Eckernforde Bay
¨
thiosulfate (10 mM) were tested as potential alternative electron enrichment, for different initial CH4 partial pressures, sulfate
acceptors for sulfate. For these experiments, sulfate-free concentrations and ∑CO2 concentrations. A more or less
medium was used. Elemental sulfur was added before closing linear correlation between the CH4 partial pressure and the
the bottles and other electron acceptors were added from stock AOM and SR rates, over the tested range, was observed. This
solutions (1.0 M). indicates that the maximum conversion rate can be found
Calculations and Estimation Conversion Rates. The at much higher CH4 partial pressures. The Michaelis Menten
volumetric AOM rate (rAOM), sulfate removal rate (rSR), and sulfide constant (Km) for CH4 is therefore at least higher than half
production rate (rSP) were estimated from the increase in ∑13CO2, of the maximum CH4 partial pressure tested, which is 0.075
the decrease in sulfate concentration, and the increase in sulfide MPa (1.1 mM). Above a sulfate concentration of 2.0 mM, the
concentration over time, respectively. A line was plotted over AOM and SR rates were independent of the sulfate concen-
the period were the increase or decrease was linear, at least tration. Only at the lowest sulfate concentration tested (0.5
four successive measurements were used. The analytical mM), the AOM and SR rates were affected. This indicates
procedures were described by Meulepas et al. (23).
that the Km for sulfate is at least lower than 2 mM. In the
incubations with an initial sulfate concentration of 0.5 mM,
∑ 13
CO2 ) f 13CO2 × P × sulfate was almost completely converted. The final concen-
(Vgas + Vliquid /k × (1 + Kz /[H+]) trations were 0.045 and 0.052 mM.
In the incubations where sulfide was allowed to ac-
cumulate, maximum dissolved sulfide concentrations of
rAOM )
(∆ ∑ 13
CO2 /∆t) 2.4((0.1) mM (N ) 4) were reached, after which both AOM
Vliquid and SR stopped (Figure 3). This inhibition was reversible, as
the conversion started again after removing the sulfide on
day 57 by flushing the liquid with CH4 gas. As a result of the
∆[SO2-]
4 stripping of H2S and CO2 from the liquid, the alkalinity
rSR ) -
∆t increased from 7.5 to 7.9, which was compensated by adding
HCl. The inhibitory effect must have been caused by sulfide,
∆[sulfide] since incubation with ∑CO2 concentrations up to 23 mM did
rSP )
∆t not show an inhibitory effect (Figure 2C).
Alternative Electron Acceptors for AOM. CH4 was
Results oxidized by the Eckernforde Bay enrichment in the presence
¨
Effect of Temperature, pH, and Salinity. Simultaneous and of sulfate, thiosulfate, and sulfite as sole available electron
stoichiometric AOM and SR by the Eckernforde Bay enrich-
¨ acceptors (Figure 4). AOM with sulfite proceeded ap-
VOL. 43, NO. 17, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 6555

4. Discussion
Effect of Temperature, pH, and Salinity on AOM and SR.
The AOM and SR rate of the Eckernforde Bay enrichment
¨
were optimal at a temperature around 20 °C. Treude et al.
(25) found a similar temperature optimum and range for
Eckernforde Bay sediment incubations. Although the AOM
¨
mediating organisms are still active at 30 °C, attempts to
grow a CH4-oxidizing sulfate-reducing microbial community
at 30 °C in membrane bioreactors inoculated with Eckern-
forde Bay sediment were not successful (23). ANME-2 were
¨
shown to be involved in AOM in Eckernforde Bay sediment
¨
(25) and by the Eckernforde Bay enrichment (23). ANME-2
¨
archaea are more adapted to low temperatures than ANME-I
(24). For biotechnological application, the low temperature
optimum forms a limitation, as most industrial wastewaters
are much warmer than 20 °C. However, in many countries
legislation requires treated wastewater to be cooled prior to
discharge. Moreover, if the wastewater is cooled in a heat
exchanger the energy loss can be minimized.
FIGURE 3. ∑13CO2 (b), sulfide (×) and sulfate (0) con- The pH and salinity optima found in this study (7.5 and
centrations over time in two duplicate batch bottles 30‰, respectively) are what can be expected for marine
inoculated with the Eckernforde Bay enrichment and with
¨ microorganisms, although at the sampling site the salinity
initially 0.13((01) MPa 13CH4 in the headspace as sole in the top 30 cm of the sediment column varies between 15
energy and carbon source. On day 57 the bottles were and 20‰ (25). Due to the high salinity requirement,
flushed and CH4 was resupplied. wastewaters low in salts (other than sulfate) can not be treated
proximately 5 times slower than with thiosulfate or sulfate. with the biomass investigated in this study. However, for
Even smaller amounts of methane were oxidized in the applications in which the liquid is recirculated (e.g., flue gas
incubations with elemental sulfur. CH4 was not oxidized by desulfurization), a high salinity optimum is an advantage,
the Eckernforde Bay enrichment in the presence of nitrate
¨ since salts accumulate in such systems.
as sole electron acceptor, nor was nitrate removed (Figure Many sulfate containing wastewaters are acid (28, 30).
4). However, below a pH of 6.5, H2S and CO2 will be the main
The utilized sulfite and elemental sulfur were not com- products of sulfate reduction, instead of HS- and HCO3-,
pletely reduced, but also partly oxidized, as sulfate was this will result in the generation of alkalinity. Therefore, a
produced (Figure 5). In addition, in the bottles without CH4, sulfate reducing bioreactor fed with acidic wastewater, can
thiosulfate and sulfite are removed as well, resulting in both often be maintained at a neutral pH.
sulfide and sulfate production (Figure 5). This can be Effect of the Methane Partial Pressure on AOM and SR.
explained by disproportionation, according to conversions The positive relation between AOM rates and the CH4 partial
6, 7, and 8 (Table 1). In the bottles with sulfite and CH4, the pressure was also found by Kruger et al. (9), Nauhaus et al.
¨
sulfide production exceeds that based on disproportionation (25), and Kallmeyer and Boetius (35), even up to a pressure
alone (Figure 5). For thiosulfate and sulfite, the net reduction of 45 MPa. This implies that ANME archaea at ambient
can be coupled to CH4 oxidation, according to conversions pressure are always limited by the CH4 availability. Thauer
2 and 3 (Table 1). In the incubations with elemental sulfur, and Shima (37) showed that the activity of the methyl-CoM
the net reduction was about half of what can be expected reductase involved in AOM depends on the CH4 concentra-
based on the CH4 oxidation rate. tion (36). In industrial applications, the availability of CH4
FIGURE 4. Net e-acceptor reduction and AOM in bottles with different electron acceptors and with or without CH4.
6556 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 17, 2009

5. FIGURE 5. Consumption and production of sulfur-compounds in bottles with different electron acceptors and with or without CH4.
for the microorganisms can be optimized by applying intermediates in the sulfate reduction pathway (41). The
thorough mixing, CH4 gas sparging and gas recirculation since Gibbs free energy change that can be obtained from CH4
this improves the contact between the CH4 gas and the oxidation coupled to thiosulfate or sulfite reduction is larger
biomass. The use of high-pressure reactors at full scale does than that with sulfate (Table 1). The activation of sulfate
not seem appealing; partly because of the energy required to APS at the cost of one ATP is not required for the other
to pressurize CH4. electron acceptors. The methyl-coenzyme M reductase,
Effect of Sulfate, ∑CO2 and Sulfide Concentrations on of which an analogue was shown to be involved in AOM
AOM and SR. The ability of the CH4-oxidizing sulfate- (42, 43) was shown to be inhibited by sulfite (44). Possibly
reducing enrichment to remove sulfate almost completely this inhibitory effect of sulfite resulted in lower rates than
(down to 0.05 mM) shows that a sulfate removal process obtained with thiosulfate. These alternative electron
with CH4 as electron donor is possible. For sites with acceptors have application possibilities as well. Thiosulfate
legislation on sulfate emissions, the maximum discharge containing wastewater is produced during pulp bleaching
concentration for sulfate is around 200 mg L-1 or 2 mM. and the fixing of photographs (32) and sulfite is the main
Measurements in the Black Sea sediment (45) and Baltic Sea compound in the liquid of flue gas scrubbing. These sulfur
(38) showed a residual sulfate concentration of a few hundred compounds can be recovered as elemental sulfur in a
µM or less beneath the sulfate to CH4 transition zone. combined anaerobic/aerobic process, as described by
The Eckernforde Bay enrichment has a low tolerance for
¨ Janssen et al. (31).
sulfide compared to the sulfide concentrations that are found Not all sulfate reducers can utilize sulfur. The Gibbs
in AOM mediating sediments. Sulfide levels in CH4 seeps free energy change for sulfur reduction with CH4 as electron
can reach up to 10 mM (39) or 15 mM (40). Also in in vitro donor is positive at standard conditions, our result show
incubations of hydrate ridge sediment, sulfide accumulated that some disproportionation and methane oxidation
to 14 mM (24). During the 3 years of enrichment, in the CH4 occurred though, but there was no clear coupling between
and sulfate fed membrane reactor operated at 15 °C, the net sulfur reduction and methane oxidation.
sulfide concentration remained below 1.5 mM due to
stripping. Therefore, microorganisms with a low tolerance
for sulfide could have become dominant. The low tolerance Acknowledgments
for sulfide forms no problem in applications in which This work was part the Anaerobic Methane Oxidation for
dissolved sulfide is continuously removed; for example, by Sulfate Reduction project (AMethOx for SuRe, number
stripping or due to precipitation with metals. EETK03044) supported by the Dutch ministryies of Eco-
Alternative Electron Acceptors for AOM. The Eckern- nomical affairs, Education, culture and science and
forde Bay enrichment was able to utilize sulfate, thiosulfate,
¨ Environment and special planning and as part their EET
and sulfite as electron acceptors for CH4 oxidation. It is (Economie, Ecologie, Technologie) program. Anna Lich-
possible that thiosulfate or sulfite were not utilized directly tschlag and Tina Treude from the MPI-Bremen are
for AOM, but that the sulfate produced by disproportion- acknowledged for providing access to the Eckernforde Bay
¨
ation was utilized by the CH4-oxidizing sulfate-reducing sediment. We thank the crew of the LITTORINA from the
community. Most sulfate reducers can use thiosulfate and Leibniz-Institut fur Meereswissenschaften for their excel-
¨
sulfite as substrates (26) though, as these compounds are lent support with the sediment sampling.
VOL. 43, NO. 17, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 6557

6. Appendix A (19) Nauhaus, K.; Boetius, A.; Kruger, M.; Widdel, W. In vitro
¨
demonstration of anaerobic oxidation of methane coupled to
sulphate reduction in sediment from a marine gas hydrate area.
NOMENCLATURE Environ. Microbiol. 2002, 4 (5), 296–30.
(20) Nauhaus, K.; Albrecht, M.; Elvert, M.; Boetius, A.; Widdel, F. In
t time vitro cell growth of marine archaeal-bacterial consortia during
anaerobic oxidation of methane with sulfate. Environ. Microbiol.
Vliquid liquid volume in serum bottle
2007, 9 (1), 187–196.
Vgas gas volume in serum bottle (21) Girguis, P. R.; Cozen, A. E.; DeLong, E. F. Growth and population
k Henry’s law constant for CO2 at sampling temper- dynamics of anaerobic methane-oxidizing archaea and sul-
ature () incubation temperature) phate-reducing bacteria in a continuous flow bioreactor. Appl.
Kz acid constant for H2CO3 dissociation Environ. Microbiol. 2005, 71, 3725–3733.
P pressure (22) Kruger, M.; Wolters, H.; Gehre, M.; Joye, S. B.; Richnow, H.-H.
¨
Tracing the slow growth of anaerobic methane-oxidizing
f fraction
communities by 15N-labelling techniques. FEMS Microbiol. Ecol.
2008, 63, 401–411.
(23) Meulepas, R. J. W.; Jagersma, C. G.; Gieteling, J.; Buisman, C. J. N.;
Literature Cited Stams, A. J. M.; Lens, P. N. L. Enrichment of anaerobic
(1) Barnes, R.; Goldberg, E. Methane production and consumption methanotrophs in a membrane bioreactor. Biotechnol. Bioeng.,
in anoxic marine sediments. Geology 1976, 4, 297–300. 2009, DOI: 10.1002/bit.22412.
(2) Martens, C. S.; Berner, R. A. Methane production in the interstitial (24) Nauhaus, K.; Treude, T.; Boetius, A.; Kruger, M. Environmental
¨
waters of sulfate-depleted marine sediments. Science 1974, 185, regulation of the anaerobic oxidation of methane: a comparison
1167–1169. of ANME-I and ANME-II communities. Environ. Microbiol. 2005,
7 (1), 98–106.
(3) Reeburgh, W. Methane consumption in Cariaco Trench waters
and sediments. Earth Planet Sci. Lett. 1976, 28, 337–344. (25) Treude, T.; Kruger, M.; Boetius, A.; Jørgensen, B. B. Environ-
¨
mental control on anaerobic oxidation of methane in the gassy
(4) Panganiban, A. T.; Patt, T. E.; Hart, W.; Hanson, R. S. Oxidation sediments of Eckernforde Bay (German Baltic). Limnol. Ocean-
¨
of methane in the absence of oxygen in lake water samples. ogr. 2005, 50, 1771–1786.
Appl. Environ. Microbiol. 1979, 37, 303–309.
(26) Widdel, F. Anaerobic degradation of hydrocarbons with sulphate
(5) Alperin, M. J.; Reeburgh, W. S. Inhibition experiments on as electron acceptor. In Sulphate-Reducing Bacteria. Barton,
anaerobic methane oxidation. Appl. Environ. Microbiol. 1985, L. L.; Hamilton, W. A. Eds.; Cambridge University Press:
50 (4), 940–945. Cambridge, UK, 2007; pp 265-303.
(6) Iversen, N.; Jørgensen, B. B. Anaerobic methane oxidation rates (27) Muyzer, G.; Stams, A. J. M. The ecology and biotechnology of
at the sulfate-methane transition in marine sediments from sulphate-reducing bacteria. Nat. Rev. Microbiol. 2008, 6, 441–
Kattegat and Skagerrak (Denmark). Limnol. Oceanogr. 1985, 30 454.
(5), 944–955. (28) Weijma, J.; Copini, C. F. M.; Buisman, C. J. N.; Schulz, C. E.
(7) Reeburgh, W. S. “Soft spots” in the global methane budget. In Biological recovery of metals, sulfur and water in the mining
Microbial Growth on C-1 Compounds; Lidstrom, M. E., Tabita, and metallurgical industry. In Water Recycling and Resource
F. R. Eds.; Kluwer Academic Publishers: Dordrecht, the Neth- Recovery in Industry: Analysis, Technologies and Implementation;
erlands, 1994; pp 334-352. Lens, P. Ed.; IWA: Londen, UK, 2002; pp 605-622.
(8) Hinrichs, K.-U.; Boetius, A. The anaerobic oxidation of methane: (29) Liamleam, W.; Annachhatre, A. P. Electron donors for biological
new insights in microbial ecology and biogeochemistry. In Ocean sulfate reduction. Biotechnol. Adv. 2007, 25, 452–463.
Margin Systems; Wefer, G., Billet, D., Hebbeln, D., Jørgensen, (30) Kaksonen, A. H.; Puhakka, J. A. Sulfate reduction based
B. B., Schluter, M., van Weering, T. Eds.; Springer-Verlag:
¨ bioprocesses for the treatment of acid mine drainage and the
Heidelberg, Germany, 2002; pp. 457-477. recovery of metals. Eng. Life Sci. 2007, 7 (6), 541–564.
(9) Kruger, M.; Treude, T.; Wolters, H.; Nauhaus, K.; Boetius, A.
¨ (31) Janssen, A. J. H.; Ruitenberg, R.; Buisman, C. J. N. Industrial
Microbial methane turnover in different marine habitats. applications of new sulphur biotechnology. Water Sci. Technol.
Palaeogeogr. Palaeoclimatol. Palaeoecol. 2005, 227, 6–17. 2001, 44 (8), 85–90.
(10) Treude, T.; Orphan, V.; Knittel, K.; Gieseke, A.; House, C. H.; (32) Lens, P. N. L.; Visser, A.; Janssen, A. J. H.; Hulshoff Pol, L. W.;
Boetius, A. Consumption of methane and CO2 by methano- Lettinga, G. Biotechnological treatment of sulfate-rich waste-
trophic microbial mats from gas seeps of the anoxic black sea. waters. Crit. Rev. Environ. Sci. Technol. 1998, 28 (1), 41–88.
Appl. Environ. Microbiol. 2007, 73 (7), 2271–2283. (33) van Houten, R. T. Biological Sulphate Reduction with Synthesis
(11) Hinrichs, K.-U.; Hayes, J. M.; Sylva, S. P.; Brewer, P. G.; DeLong, Gas. PhD Thesis, Wageningen University: Wageningen, The
E. F. Methane-consuming archaebacteria in marine sediments. Netherlands, 1996.
Nature 1999, 398, 802–805. (34) Mueller-Langer F.; Tzimas E.; Kaltschmitt M.; Peteves S. Techno-
economic assessment of hydrogen production processes for
(12) Orphan, V. J.; House, C. H.; Hinrichs, K.-U.; McKeegan, K. D.;
the hydrogen economy for the short and medium term. Int. J.
DeLong, E. F. Multiple archaeal groups mediate methane
Hydrogen Energy 2007, 32, 3797-3810.
oxidation in anoxic cold seep sediments. Proc. Natl. Acad. Sci.
(35) Kallmeyer, J.; Boetius, A. Effects of temperature and pressure
U. S. A. 2002, 99, 7663–7668.
on sulfate reduction and anaerobic oxidation of methane in
(13) Boetius, A.; Ravenschlag, K.; Schubert, C. J.; Rickert, D.; Widdel, hydrothermal sediments of Guaymas basin. Appl. Environ.
F.; Gieseke, A.; Amann, R.; Jørgensen, B. B.; Witte, U.; Pfann- Microbiol. 2004, 70 (20), 1231–1233.
kuche, O. A marine microbial consortium apparently mediating (36) Shima, S.; Thauer, R. K. Methyl-coenzyme M reductase and the
anaerobic oxidation of methane. Nature 2000, 407, 623–626. anaerobic oxidation of methane in methanotrophic Archaea.
(14) Michaelis, W.; Seifert, R.; Nauhaus, K.; Treude, T.; Thiel, V.; Curr. Opin. Microbiol. 2005, 8, 643–648.
Blumenberg, M.; Knittel, K.; Gieseke, A.; Peterknecht, K.; Pape, (37) Thauer, R. K.; Shima, S. Methane as fuel for anaerobic organisms.
T.; Boetius, A.; Amann, R.; Jørgensen, B. B.; Widdel, F.; Peckmann, Ann. N. Y. Acad. Sci. 2008, 1125, 158–170.
J.; Pimenov, N. V.; Gulin, M. B. Microbial reefs in the Black Sea (38) Knab, N. J.; Cragg, B. A.; Borowski, C.; Parkes, R. J.; Pancost, R.;
fueled by anaerobic oxidation of methane. Science 2002, 297, Jørgensen, B. B. Anaerobic oxidation of methane (AOM) in
1014–1015. marine sediments from the Skagerrak (Denmark): I. Geochemi-
(15) Knittel, K.; Losekann, T.; Boetius, A.; Kort, R.; Amann, R. Diversity
¨ cal and microbiological analyses. Geochim. Cosmochim. Acta
and distribution of methanotrophic archaea at cold seeps. Appl. 2008, 72, 2868–2879.
Environ. Microbiol. 2005, 71, 467–479. (39) Joye, A. B.; Boetius, A.; Orcutt, B. N.; Montoya, J. P.; Schulz,
(16) Zehnder, A. J. B.; Brock, T. D. Anaerobic methane oxidation: H. N.; Erickson, M. J.; Lugo, S. K. The anaerobic oxidation of
occurrence and ecology. Appl. Environ. Microbiol. 1980, 39 (1), methane and sulfate reduction in sediments from Gulf of Mexico
194–204. cold seeps. Chem. Geol. 2005, 205, 219–238.
(17) Hoehler, T. M.; Alperin, M. J.; Albert, D. B.; Martens, C. S. Field (40) Valentine, D. L Biogeochemistry and microbial ecology of
and laboratory studies of methane oxidation in an anoxic marine methane oxidation in anoxic environments: a review. Antonie
sediment: Evidence for a methanogen-sulfate reducer consor- van Leeuwenhoek 2002, 81, 271–282.
tium. Global Biogeochem. cycles 1994, 8 (4), 451–463. (41) Widdel, F.; Hansen, T. A. The dissimilatory sulfate- and
(18) DeLong, E. F. Resolving a methane mystery. Nature 2000, 407, sulfurreducing bacteria. In The Prokaryotes, 2nd ed.; Balows,
577–579. A., Truper, H. G., Dworkin, M., Harder, W., Schleifer, K.-H.,
¨
6558 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 43, NO. 17, 2009

7. Eds.; Springer-Verlag: New York, N.Y., 1992; Vol. I, pp 583- EPR signals from MCR-red2. J. Biol. Inorg. Chem. 2002, 7, 500–
624. 513.
(42) Hallam, S. J.; Girguis, P. R.; Preston, C. M.; Richardson, P. M.; (45) Neretin, L. N.; Bottcher, M. E.; Jørgensen, B. B.; Volkov, I. I.;
¨
DeLong, E. F. Identification of methyl coenzyme M reductase Lu¨schen, H.; Hilgenfeldt, K. Pyrite formation via greigite in limnic
A (mcrA) genes associated with methaneoxidizing archaea. Appl. sediments of the Black Sea. Geochim. Cosmochim. Acta 2004,
Environ. Microbiol. 2003, 69, 5483–5491. 68, 2081–2093.
(43) Kruger, M.; Meyerdierks, A.; Glockner, F. O.; Amann, R.;
¨ ¨ (46) Thauer, R. K.; Jungermann, K.; Decker, K. Energy conservation
Widdel, F.; Kube, Reinhardt, R.; Kahnt, J.; Bocher, R.; Thauer,
¨ in chemotrophic anaerobic bacteria. Bacteriol. Rev. 1977, 41,
R. K.; Shima, S. A conspicuous nickel protein in microbial 100–180.
mats that oxidize methane anaerobically. Nature 2003, 426,
878–881.
(44) Mahlert, F.; Bauer, C.; Jaun, B.; Thauer, R. K.; Duin, E. C. The
nickel enzyme methyl-coenzyme M reductase from methano-
genic archaea: in vitro induction of the nickel-based MCR-ox ES900633C
VOL. 43, NO. 17, 2009 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 6559