Ecophysiology of sulfate-reducing bacteria and syntrophic communities in marine anoxic sediments
Özüölmez, Deya - \ 2017
Wageningen University. Promotor(en): A.J.M. Stams; Caroline M. Plugge. - Wageningen : Wageningen University - ISBN 9789463436540 - 225
degradation - marine sediments - methanobacteria - microorganisms - organic matter - anoxia - sulfate reduction - degradatie - mariene sedimenten - methanobacteria - micro-organismen - organische stof - anoxie - sulfaatreductie
Propionate, butyrate, acetate, hydrogen and formate are the major intermediates of organic matter degradation. Sulfate-reducing bacteria (SRB) contribute significantly to the consumption of these substrates in sulfate-rich marine sediments. In sulfate-depleted sediments, however, complete degradation of propionate or butyrate is only possible via syntrophic cooperation of acetogenic bacteria and methanogenic archaea. Despite that the predominance of SRB in sulfate-rich and methanogens in sulfate-depleted sediments was reported, recent studies showed that both types of microorganism could be present in upper and lower parts of marine sediments. In this thesis, propionate and butyrate conversions and the involved microbial community in sulfate, sulfate-methane transition and methane zone sediment of Aarhus Bay, Denmark were studied using sediment slurry incubations. Interspecies hydrogen transfer and coexistence during acetate degradation were investigated in mixed pure cultures.
In Chapter 2, interspecies hydrogen transfer between aceticlastic Methanosaeta concilii and hydrogenotrophic microorganisms, Desulfovibrio vulgaris or Methanococcus maripaludis, was investigated. Additionally, coexistence of M. concilii and Desulfobacter latus growing on acetate under sulfidogenic conditions was studied. The results of Chapter 2 showed that D. vulgaris could reduce sulfate and grow on leaked hydrogen from M. concilii. Hydrogen leakage from M. concilii provides an explanation for biogeochemical zonation both for competitive (e.g. acetate) and non-competitive substrates (methyl compounds), and this indicates the possible coexistence of SRB and methanogens in sulfate-rich environments.
In chapter 3 and 4, long term incubations were examined focusing on butyrate and propionate conversion and the microbial community dynamics in sediment slurry enrichments at different sulfate (o, 3 and 20 mM) concentrations and incubation temperatures (10°C and 25°C). Sulfate reduction is the dominant process for butyrate and propionate conversion in Aarhus Bay sediments. In the absence of sulfate, both substrates can be converted efficiently, indicating the presence of syntrophic communities throughout the sediment. The fluctuating methane concentrations and the enrichment of anaerobic methanotrophic archaea (ANME) during butyrate and propionate conversion at 10°C suggest the occurrence of anaerobic oxidation of methane (AOM) in sulfate-methane transition zone (SMTZ) of Aarhus Bay.
The microbial community involved in butyrate and propionate conversions were investigated using next generation sequencing (NGS) of the 16S rRNA amplicon sequencing. The enriched sulfate-reducing bacteria at high sulfate concentration (20 mM) were different when butyrate and propionate were used as substrate. Desulfosarcina and Desulfobacterium dominate the butyrate-converting slurries (Chapter 3), whereas Desulfosarcina, Desulfobulbus and Desulforhopalus are the main SRB in propionate-converting slurries (Chapter 4). The increase in the relative abundance of Desulfobacteraceae and Desulfobulbaceae in SZ, SMTZ and MZ sediment slurries suggests the presence of sulfate reducers throughout the anoxic sediment column. In the absence of sulfate, Syntrophomonas and Cyrptanaerobacter become dominant which suggests their role in syntrophic butyrate and propionate conversion, respectively. These results were further supported in Chapter 6. The increase in the relative abundance of Syntrophomonas in the presence of sulfate (Chapter 3) and some members of Desulfobacteraceae (Chapter 4) in the absence of sulfate shows the metabolic flexibility of the microorganisms at different sulfate concentrations. Temperature has an impact on the microbial community (Chapter 4) and IPL composition (Chapter 5) in enrichment slurries. Cryptanaerobacter is dominant at 25°C, and, Desulfobacteraceae (Desulfofaba), especially Desulfobulbaceae members (Desulfobulbus, Desulforhopalus) become dominant at 10°C at 0 and 3 mM sulfate concentrations in propionate-amended enrichment slurries. In butyrate-amended slurries, Clostridiales have higher relative abundance at 10°C regardless of the sulfate concentration and the sediment depth which supports important role of Clostridiales in butyrate conversion in marine sediments. Archaeal community analyses revealed the dominance of hydrogenotrophic methanogens belonging to Methanomicrobiales in both butyrate- and propionate-converting slurries (Chapter 3 and 4) and enrichment cultures (Chapter 6) regardless of the sediment depth, the incubation temperature and the presence of sulfate, which indicate that they are the main syntrophic partners of butyrate and propionate degraders. The other syntrophic partner organisms are the aceticlastic methanogenic families: Methanosarcinaceae and Methanosaetaeceae. The presence of methane-oxidizing archaea (ANME-1b) in low temperature SMTZ slurries together with Desulfobacteraceae (Chapter 3 and 4) suggests the occurrence of anaerobic oxidation of methane (AOM) in SMTZ of Aarhus Bay.
In conclusion, this thesis confirms the presence and activity of methanogens in sulfate-rich, and SRB in sulfate-depleted marine sediments; and their involvement in butyrate, propionate and acetate conversion. Novel bacterial and archaeal members enriched in the sediment slurries are likely involved in propionate, butyrate and acetate conversions at different depths of marine sediments in addition to known the cultured species.
Simultaneous sulfate reduction and metal precipitation in an inverse fluidized bed reactor
Villa Gomez, D.K. - \ 2013
Wageningen University. Promotor(en): Piet Lens, co-promotor(en): Karel Keesman. - [S.l.] : S.n. - ISBN 9789461737410 - 194
wervelbedden - uitrusting - sulfaatreductie - chemische precipitatie - metalen - fluidized beds - equipment - sulfate reduction - chemical precipitation - metals
Selective recovery of nickel over iron from a nickel-iron solution using microbial sulfate reduction in a gas-lift bioreactor
Bijmans, M.F.M. ; Helvoort, P.J. van; Dar, S. ; Dopson, M. ; Lens, P.N.L. ; Buisman, C.J.N. - \ 2009
Water Research 43 (2009)3. - ISSN 0043-1354 - p. 853 - 861.
mijnbouw - metallurgie - mijnafval - slib - waterstof - ijzer - nikkel - bioreactoren - elektroforese - sulfaatreductie - slibzuivering - verwijdering - mining - metallurgy - mine tailings - sludges - hydrogen - iron - nickel - bioreactors - electrophoresis - sulfate reduction - sludge treatment - removal - gradient gel-electrophoresis - sulfide precipitation - metal precipitation - heavy-metals - soils - water - ores
Process streams with high concentrations of metals and sulfate are characteristic for the mining and metallurgical industries. This study aims to selectively recover nickel from a nickel-iron-containing solution at pH 5.0 using a single stage bioreactor that simultaneously combines low pH sulfate reduction and metal-sulfide formation. The results show that nickel was selectively precipitated in the bioreactor at pH 5.0 and the precipitates consisted of >or=83% of the nickel content. The nickel-iron precipitates were partly crystalline and had a metal/sulfur ratio of 1, suggesting these precipitates were NiS and FeS. Experiments focusing on nickel recovery at pH 5.0 and 5.5 reached a recovery of >99.9%, resulting in a nickel effluent concentration
Microbial aspects of anaerobic methane oxidation with sulfate as electron acceptor
Jagersma, C.G. - \ 2009
Wageningen University. Promotor(en): Fons Stams, co-promotor(en): Piet Lens. - [S.l. : S.n. - ISBN 9789085855118 - 181
methaan - anaërobe omstandigheden - sulfaatreductie - anaërobe microbiologie - methane - anaerobic conditions - sulfate reduction - anaerobic microbiology
Anaerobic oxidation of methane (AOM) is an important methane sink in the ocean but the microbes responsible for AOM are as yet resilient to cultivation. It was shown that AOM was coupled to sulfate reduction (SR) and this gave rise to current research which aims to develop a biotechnological process in which methane is used an electron donor for SR.
This thesis describes the microbial analysis of an enrichment capable of high rate AOM (286 µmol.gdry weight-1.day-1) coupled to SR using a novel submerged membrane bioreactor system. Initially AOM rates were extremely low (0.004 mmol L-1 d-1), but AOM and SR increased exponential over the course of 884 days to 0.60 mmol L-1 d-1. The responsible organisms doubled every 3.8 months.
By constructing a clone library with subsequent sequencing and fluorescent in situ hybridization (FISH), we showed that the responsible methanotrophs belong to the ANME-2a subgroup of anaerobic methanotrophic archaea, and that sulfate reduction is most likely performed by sulfate reducing bacteria commonly found in association with other ANME related archaea in marine sediments. Another relevant portion of the bacterial sequences can be clustered within the order of Flavobacteriales but their role remains to be elucidated. FISH analyses showed that the ANME-2a cells occur as single cells without close contact to the bacterial syntrophic partner. Incubation with 13C labeled methane showed substantial incorporation of 13C label in the bacterial C16 fatty acids (bacterial; 20, 44 and 49%) and in archaeal lipids, archaeol and hydroxyl-archaeol (21 and 20%, respectively). This confirms that both archaea and bacteria are responsible for the anaerobic methane oxidation in a bioreactor enrichment inoculated with Eckernförde bay sediment. To unravel the pathway of this syntrophic conversion, the effect of possible intermediates on AOM and SR was assessed.
To investigate which kind of waste and process streams can be treated by the methanotrophic sulfate-reducing enrichment, the effect of environmental conditions and different substrates was assessed. The optimum pH, salinity and temperature for SR with methane by the enrichment were 7.5, 30‰ and 20°C, respectively. The biomass had a good affinity for sulfate (Km < 1.0 mM), a low affinity for methane (Km > 75 KPa) and AOM was completely inhibited at 2.4 (±0.1) mM sulfide. The enrichment utilized sulfate, thiosulfate, sulfite and elemental sulfur as alternative electron acceptors for methane oxidation and formate, acetate and hydrogen as alternative electron donors for sulfate reduction. As a co-substrate for methane oxidation only methanol stimulated the conversion of 13C labeled CH4 to 13CO2 in batch incubations of Eckernförde bay sediment, other possible co-substrates had a negative effect on the AOM rate.
The research described in this thesis shows the possibility of enriching slow growing methane oxidizing communities but also shows the difficulties in applying this process for a biotechnological purpose because of the extreme slow doubling times and the lack of understanding of the metabolic routes used by these organisms.
Biotechnological aspects of anaerobic oxidation of methane coupled to sulfate reduction
Meulepas, R.J.W. - \ 2009
Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Piet Lens; Fons Stams. - [S.l. : S.n. - ISBN 9789085853978 - 173
anaërobe omstandigheden - oxidatie - methaan - microbiologie - biotechnologie - anaërobe microbiologie - sulfaatreductie - anaerobic conditions - oxidation - methane - microbiology - biotechnology - anaerobic microbiology - sulfate reduction
Sulfate reduction (SR) can be used for the removal and recovery of metals and oxidized sulfur compounds from waste streams. Sulfate-reducing bacteria reduce oxidized sulfur compounds to sulfide. Subsequently, sulfide can precipitate dissolved metals or can be oxidized to elemental sulfur. Both metal sulfides and elemental sulfur can be reused in various applications. SR with hydrogen or ethanol as electron donor is an established biotechnological process. However, the costs of these electron donors limit the application possibilities. Methane would be a cheaper and more attractive electron donor. SR coupled to the anaerobic oxidation of methane (AOM) occurs in marine sediments. Uncultured archaea, distantly related to methanogens, and bacteria are involved in this process. The in vitro demonstration of SR coupled to AOM gave rise to this research, which aims to develop a biotechnological process in which methane is used as electron donor for SR.
Three types of anaerobic granular sludge were screened for the ability to reduce sulfate with methane as electron donor. To do so, incubations were done with 13C-labeled methane. All three sludge types anaerobically oxidized 13C-labeled methane to 13C-labeled carbon dioxide. Moreover, the presence of methane enhanced the SR rate. However, AOM by sludge was not coupled to SR, but coincides with net methanogenesis. The methane-dependent SR was caused by the inhibitory effect of methane on methanogens competing (possibly in syntrophic consortia with acetogenic bacteria) with sulfate reducers for the same endogenous substrate. Therefore, anaerobic granular sludge does not form a suitable inoculum for sulfate-reducing bioreactors fed with methane.
Well-mixed ambient-pressure submersed-membrane bioreactors, fed with sulfate and methane, were inoculated with sediment from Eckernförde Bay (Baltic Sea). Initially AOM rates were extremely low (0.004 mmol L-1 day-1), but at 15ºC AOM and SR rates increased over the course of 884 days to 0.60 mmol L-1 day-1 or 1.0 mmol gVSS-1 day-1. The AOM rate doubled approximately every 3.8 months. Molecular analyses revealed that the archaea in the obtained enrichment belonged predominately to the anaerobic methanotroph ANME-2a. Both bacteria and archaea incorporated carbon derived from 13C-labeled methane into their lipids, indicating that both were involved in AOM coupled to SR. To investigate which kind of waste streams can be treated by the methane-oxidizing sulfate-reducing enrichment, the effect of environmental conditions and alternative substrates on AOM and SR was assessed. The optimum pH, salinity and temperature for SR with methane by the enrichment were 7.5, 30‰ and 20°C, respectively. The biomass had a good affinity for sulfate (Km 1.0 mM), a low affinity for methane (Km > 75 kPa) and AOM was completely inhibited by 2.4 (±0.1) mM sulfide. The enrichment utilized sulfate, thiosulfate and sulfite as electron acceptors for methane oxidation, and methane, formate, acetate and hydrogen as electron donors for SR.
This study shows that methane can be used as electron donor for sulfate reduction in bioreactors. However, the low growth rate of the responsible microorganisms still forms a major bottleneck for biotechnological applications.
Selenate removal in methanogenic and sulfate-reducing upflow anaerobic sludge bed reactors
Lenz, M. ; Hullebusch, E.D. van; Hommes, G. ; Corvini, P.F.X. ; Lens, P.N.L. - \ 2008
Water Research 42 (2008)8-9. - ISSN 0043-1354 - p. 2184 - 2194.
afvalwaterbehandeling - bioreactoren - slib - selenium - verwijdering - efficiëntie - biologische filtratie - slibzuivering - sulfaatreductie - waste water treatment - bioreactors - sludges - selenium - removal - efficiency - biological filtration - sludge treatment - sulfate reduction - acid-mine drainage - granular sludge - elemental selenium - respiring bacteria - waste-water - se - reduction - sediments - coal - particulate
This paper evaluates the use of upflow anaerobic sludge bed (UASB) bioreactors (30 degrees C, pH = 7.0) to remove selenium oxyanions from contaminated waters (790 mu g Se L-1) under methanogenic and sulfate-reducing conditions using lactate as electron donor. One UASB reactor received sulfate at different sulfate to selenate ratios, while another UASB was operated under methanogenic conditions for 132 days without sulfate in the influent. The selenate effluent concentrations in the sulfate-reducing and methanogenic reactor were 24 and 8 mu gSeL(-1), corresponding to removal efficiencies of 97% and 99%, respectively. X-ray diffraction (XRD) analysis and sequential extractions showed that selenium was mainly retained as elemental selenium in the biomass. However, the total dissolved selenium effluent concentrations amounted to 73 and 80 mu gSeL(-1), respectively, suggesting that selenate was partly converted to another selenium compound, most likely colloidally dispersed Sea nanoparticles. Possible intermediates of selenium reduction (selenite, dimethylselenide, dimethyldiselenide, H2Se) could not be detected. Sulfate reducers removed selenate at molar excess of sulfate to selenate (up to a factor of 2600) and elevated dissolved sulfide concentrations (up to 168mgL(-1)), but selenium removal efficiencies were limited by the applied sulfate-loading rate. in the methanogenic bioreactor, selenate and dissolved selenium removal were independent of the sulfate load, but inhibited by sulfide (101 mg L-1). The selenium removal efficiency of the methanogenic UASB abruptly improved after 58 days of operation, suggesting that a specialized selenium-converting population developed in the reactor. This paper demonstrates that both sulfate-reducing and methanogenic UASB reactors can be applied to remove selenate from contaminated natural waters and anthropogenic waste streams, e.g. agricultural drainage waters, acid mine drainage and flue gas desulfurization bleeds.
High rate sulfate reduction at pH 6 in a Ph-auxostat submerged membrane bioreactor fed with formate
Bijmans, M.F.M. ; Peeters, T.W.T. ; Lens, P.N.L. ; Buisman, C.J.N. - \ 2008
Water Research 42 (2008)10-11. - ISSN 0043-1354 - p. 2439 - 2448.
afvalwaterbehandeling - industrieel afval - bioreactoren - membranen - filtratie - sulfaat reducerende bacteriën - sulfaatreductie - waste water treatment - industrial wastes - bioreactors - membranes - filtration - sulfate reducing bacteria - sulfate reduction - gas-lift reactor - reducing bacteria - hydrogen-sulfide - carbon-dioxide - growth - methanogenesis - conversion - removal - sludge - water
Many industrial waste and process waters contain high concentrations of sulfate, which can be removed by sulfate-reducing bacteria (SRB). This paper reports on mesophilic (30 °C) sulfate reduction at pH 6 with formate as electron donor in a membrane bioreactor with a pH-auxostat dosing system. A mixed microbial community from full-scale industrial wastewater treatment bioreactors operated at pH 7 was used as inoculum. The pH-auxostat enabled the bacteria to convert sulfate at a volumetric activity of 302 mmol sulfate reduced per liter per day and a specific activity of 110 mmol sulfate reduced per gram volatile suspended solids per day. Biomass grew in 15 days from 0.2 to 4 g volatile suspended solids per liter. This study shows that it is possible to reduce sulfate at pH 6 with formate as electron donor at a high volumetric and specific activity with inocula from full-scale industrial wastewater treatment bioreactors operated at neutral pH. The combination of a membrane bioreactor and a pH-auxostat is a useful research tool to study processes with unknown growth rates at maximum activities.
Sulfate reduction under acidic conditions for selective model recovery
Bijmans, M.F.M. - \ 2008
Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Piet Lens. - [S.l.] : S.n. - ISBN 9789085049258 - 156
sulfaat - redoxreacties - zuurgraad - metalen - terugwinning - afvalwaterbehandeling - bioreactoren - nikkel - ijzer - sulfaatreductie - sulfate - redox reactions - acidity - metals - recovery - waste water treatment - bioreactors - nickel - iron - sulfate reduction
Dit proefschrift heeft als doel om processen te ontwikkelen voor selectieve metaal herwinning uit afvalwater and processtromen die meerdere metalen bevatten, door gebruik te maken van sulfaat reductie onder zure omstandigheden
Sulfate reduction at low pH in organic wastewaters
Lopes, S.I.C. - \ 2007
Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): P. Lens; M.I. Capela. - [S.l.] : S.n. - ISBN 9789085047636 - 244
afvalwaterbehandeling - ph - verzuring - sulfaten - anaërobe behandeling - sulfaatreductie - waste water treatment - ph - acidification - sulfates - anaerobic treatment - sulfate reduction
The objective of the research described in this thesis was to investigate the operational window of dissimilatory sulfate reduction at low pH (6, 5 and 4) during the acidification of organic wastewaters. High sulfate reduction efficiencies at low pH are desirable for a more sustainable operation of acidification reactors in a two-phase wastewater treatment system, as pH control requires less caustic and/or the effluent recirculation from the second (methanogenic) reactor can be skipped. The low pH would also facilitate the removal of sulfide by stripping, as the fraction of gaseous sulfide increases with decreasing pH