Haloalkaline thiosulfate reducing bioreactor
Ontology highlight
ABSTRACT:
PROVIDER: PRJEB11708 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| ERR1121450_1.fastq.gz | Fastqsanger.gz | |||
| ERR1121450_2.fastq.gz | Fastqsanger.gz | |||
| ERR1121451_1.fastq.gz | Fastqsanger.gz | |||
| ERR1121451_2.fastq.gz | Fastqsanger.gz |
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Project description:Biodesulfurization processes remove toxic and corrosive hydrogen sulfide from gas streams (e.g., natural gas, biogas, or syngas). To improve the efficiency of these processes under haloalkaline conditions, a sulfate and thiosulfate reduction step can be included. The use of H2/CO mixtures (as in syngas) instead of pure H2 was tested to investigate the potential cost reduction of the electron donor required. Syngas is produced in the gas-reforming process and consists mainly of H2, carbon monoxide (CO), and carbon dioxide (CO2). Purification of syngas to obtain pure H2 implies higher costs because of additional post-treatment. Therefore, the use of syngas has merit in the biodesulfurization process. Initially, CO inhibited hydrogen-dependent sulfate reduction. However, after 30 days the biomass was adapted and both H2 and CO were used as electron donors. First, formate was produced, followed by sulfate and thiosulfate reduction, and later in the reactor run acetate and methane were detected. Sulfide production rates with sulfate and thiosulfate after adaptation were comparable with previously described rates with only hydrogen. The addition of CO marginally affected the microbial community in which Tindallia sp. was dominant. Over time, acetate production increased and acetogenesis became the dominant process in the bioreactor. Around 50% of H2/CO was converted to acetate. Acetate supported biomass growth and higher biomass concentrations were reached compared to bioreactors without CO feed. Finally, CO addition resulted in the formation of small, compact microbial aggregates. This suggests that CO or syngas can be used to stimulate aggregation in haloalkaline biodesulfurization systems.
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Project description:Recently, sulfate-reducing granular sludge has been developed for application in sulfate-laden water and wastewater treatment. However, little is known about biomass stratification and its effects on the bioprocesses inside the granular bioreactor. A comprehensive investigation followed by a verification trial was therefore conducted in the present work. The investigation focused on the performance of each sludge layer, the internal hydrodynamics and microbial community structures along the height of the reactor. The reactor substratum (the section below baffle 1) was identified as the main acidification zone based on microbial analysis and reactor performance. Two baffle installations increased mixing intensity but at the same time introduced dead zones. Computational fluid dynamics simulation was employed to visualize the internal hydrodynamics. The 16S rRNA gene of the organisms further revealed that more diverse communities of sulfate-reducing bacteria (SRB) and acidogens were detected in the reactor substratum than in the superstratum (the section above baffle 1). The findings of this study shed light on biomass stratification in an SRB granular bioreactor to aid in the design and optimization of such reactors.
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Project description:Thermophilic sulfide-producing microorganisms from an oil pipeline network were enumerated with different sulfur oxyanions as electron acceptors at 55°C. Most-probable number (MPN) analysis showed that thiosulfate-reducing bacteria were the most numerous sulfidogenic microorganisms in pipeline inspection gauge (PIG) scrapings. Thiosulfate-reducing and methanogenic enrichments were obtained from the MPN cultures that were able to use yeast extract as the electron donor. Molecular analysis revealed that both enrichments harbored the same dominant bacterium, which belonged to the genus Anaerobaculum. The dominant archaeon in the methanogenic enrichment was affiliated with the genus Methanothermobacter. With yeast extract as the electron donor, the general corrosion rate by the thiosulfate-reducing enrichment (8.43 ± 1.40 milli-inch per year, abbreviated as mpy) was about 5.5 times greater than the abiotic control (1.49 ± 0.15 mpy), while the comparable measures for the methanogenic culture were 2.03 ± 0.49 mpy and 0.62 ± 0.07 mpy, respectively. Total iron analysis in the cultures largely accounted for the mass loss of iron measured in the weight loss determinations. Profilometry analysis of polished steel coupons incubated in the presence of the thiosulfate-reducing enrichment revealed 59 pits over an area of 71.16 mm(2), while only 6 pits were evident in the corresponding methanogenic incubations. The results show the importance of thiosulfate-utilizing, sulfide-producing fermentative bacteria such as Anaerobaculum sp. in the corrosion of carbon steel, but also suggest that Anaerobaculum sp. are of far less concern when growing syntrophically with methanogens.
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Project description:Nitric oxide (NO) is a highly reactive and climate-active molecule and a key intermediate in the microbial nitrogen cycle. Despite its role in the evolution of denitrification and aerobic respiration, high redox potential and capacity to sustain microbial growth, our understanding of NO-reducing microorganisms remains limited due to the absence of NO-reducing microbial cultures obtained directly from the environment using NO as a substrate. Here, using a continuous bioreactor and a constant supply of NO as the sole electron acceptor, we enriched and characterized a microbial community dominated by two previously unknown microorganisms that grow at nanomolar NO concentrations and survive high amounts (>6 µM) of this toxic gas, reducing it to N2 with little to non-detectable production of the greenhouse gas nitrous oxide. These results provide insight into the physiology of NO-reducing microorganisms, which have pivotal roles in the control of climate-active gases, waste removal, and evolution of nitrate and oxygen respiration.
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Project description:Although the oxidative condensation of two thiosulfate anions to tetrathionate constitutes a well documented and significant part of the natural sulfur cycle, little is known about the enzymes catalyzing this reaction. In the purple sulfur bacterium Allochromatium vinosum, the reaction is catalyzed by the periplasmic diheme c-type cytochrome thiosulfate dehydrogenase (TsdA). Here, we report the crystal structure of the "as isolated" form of A. vinosum TsdA to 1.98 Å resolution and those of several redox states of the enzyme to different resolutions. The protein contains two typical class I c-type cytochrome domains wrapped around two hemes axially coordinated by His(53)/Cys(96) and His(164)/Lys(208). These domains are very similar, suggesting a gene duplication event during evolution. A ligand switch from Lys(208) to Met(209) is observed upon reduction of the enzyme. Cys(96) is an essential residue for catalysis, with the specific activity of the enzyme being completely abolished in several TsdA-Cys(96) variants. TsdA-K208N, K208G, and M209G variants were catalytically active in thiosulfate oxidation as well as in tetrathionate reduction, pointing to heme 2 as the electron exit point. In this study, we provide spectroscopic and structural evidence that the TsdA reaction cycle involves the transient presence of heme 1 in the high-spin state caused by movement of the Sγ atom of Cys(96) out of the iron coordination sphere. Based on the presented data, we draw important conclusions about the enzyme and propose a possible reaction mechanism for TsdA.
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Project description:Communities of anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria (SRB) grow slowly, which limits the ability to perform physiological studies. High methane partial pressure was previously successfully applied to stimulate growth, but it is not clear how different ANME subtypes and associated SRB are affected by it. Here, we report on the growth of ANME-SRB in a membrane capsule bioreactor inoculated with Eckernförde Bay sediment that combines high-pressure incubation (10.1 MPa methane) and thorough mixing (100 rpm) with complete cell retention by a 0.2-m-pore-size membrane. The results were compared to previously obtained data from an ambient-pressure (0.101 MPa methane) bioreactor inoculated with the same sediment. The rates of oxidation of labeled methane were not higher at 10.1 MPa, likely because measurements were done at ambient pressure. The subtype ANME-2a/b was abundant in both reactors, but subtype ANME-2c was enriched only at 10.1 MPa. SRB at 10.1 MPa mainly belonged to the SEEP-SRB2 and Eel-1 groups and the Desulfuromonadales and not to the typically found SEEP-SRB1 group. The increase of ANME-2a/b occurred in parallel with the increase of SEEP-SRB2, which was previously found to be associated only with ANME-2c. Our results imply that the syntrophic association is flexible and that methane pressure and sulfide concentration influence the growth of different ANME-SRB consortia. We also studied the effect of elevated methane pressure on methane production and oxidation by a mixture of methanogenic and sulfate-reducing sludge. Here, methane oxidation rates decreased and were not coupled to sulfide production, indicating trace methane oxidation during net methanogenesis and not anaerobic methane oxidation, even at a high methane partial pressure.
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Project description:The strain WBS, an anaerobic, psychro- and halotolerant bacterium belonging to the genus Fusibacter, was isolated from the littoral bottom sediments of the White Sea, Arctic, Russia. Fusibacter bizertensis WBS grew at temperatures between 8 and 32 °C (optimum growth at 18-20 °C), pH between 5.2 and 8.3 (optimum growth at pH 7.2), and at NaCl concentrations between 0 and 70 g L-1 (optimum growth at 32 g L-1). It reduced sulfate, thiosulfate, and elemental sulfur into sulfide, and, probably, the strain is able to disproportionate thiosulfate. The strain also utilized a wide range of substrates as it is a chemoorganotrophic bacterium. Analysis of the sequenced genome revealed genes for all enzymes involved in the Embden-Meyerhof glycolytic pathway as well as genes for the non-oxidative stage of the pentose phosphate pathway. The presence of genes encoding aldehyde dehydrogenases and alcohol dehydrogenases also suggests that, in addition to acetate, alcohols can also be the fermentation products. The strain possessed superoxide dismutase and peroxidase activities and the ability to consume O2, which is in full accordance with the presence of corresponding genes of antioxidant defense in the genome. The phylogenetic analysis suggested that the strain WBS is the closest relative of Fusibacter bizertensis LTF Kr01T (16S rRNA gene sequence similarity 98.78%). Based on biochemical and genomic characteristics, the strain WBS is proposed to represent a novel aero-, halo- and psychrotolerant strain from the genus Fusibacter, isolated for the first time among its members from cold oxygenated marine bottom sediments.
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