scholarly journals Effects of Sulfate Reduction on Trichloroethene Dechlorination by Dehalococcoides-Containing Microbial Communities

2017 ◽  
Vol 83 (8) ◽  
Author(s):  
Xinwei Mao ◽  
Alexandra Polasko ◽  
Lisa Alvarez-Cohen
Keyword(s):  
Microbial Communities ◽  
Sulfate Reduction ◽  
Electron Donor ◽  
Reductive Dechlorination ◽  
Sulfate Reducer ◽  
Content Type ◽  
Dehalococcoides Mccartyi ◽  
Sulfide Inhibition ◽  
Genes Encoding ◽  
High Sulfate

ABSTRACT In order to elucidate interactions between sulfate reduction and dechlorination, we systematically evaluated the effects of different concentrations of sulfate and sulfide on reductive dechlorination by isolates, constructed consortia, and enrichments containing Dehalococcoides sp. Sulfate (up to 5 mM) did not inhibit the growth or metabolism of pure cultures of the dechlorinator Dehalococcoides mccartyi 195, the sulfate reducer Desulfovibrio vulgaris Hildenborough, or the syntroph Syntrophomonas wolfei. In contrast, sulfide at 5 mM exhibited inhibitory effects on growth of the sulfate reducer and the syntroph, as well as on both dechlorination and growth rates of D. mccartyi. Transcriptomic analysis of D. mccartyi 195 revealed that genes encoding ATP synthase, biosynthesis, and Hym hydrogenase were downregulated during sulfide inhibition, whereas genes encoding metal-containing enzymes involved in energy metabolism were upregulated even though the activity of those enzymes (hydrogenases) was inhibited. When the electron acceptor (trichloroethene) was limiting and an electron donor (lactate) was provided in excess to cocultures and enrichments, high sulfate concentrations (5 mM) inhibited reductive dechlorination due to the toxicity of generated sulfide. The initial cell ratio of sulfate reducers to D. mccartyi (1:3, 1:1, or 3:1) did not affect the dechlorination performance in the presence of sulfate (2 and 5 mM). In contrast, under electron donor limitation, dechlorination was not affected by sulfate amendments due to low sulfide production, demonstrating that D. mccartyi can function effectively in anaerobic microbial communities containing moderate sulfate concentrations (5 mM), likely due to its ability to outcompete other hydrogen-consuming bacteria and archaea. IMPORTANCE Sulfate is common in subsurface environments and has been reported as a cocontaminant with chlorinated solvents at various concentrations. Inconsistent results for the effects of sulfate inhibition on the performance of dechlorination enrichment cultures have been reported in the literature. These inconsistent findings make it difficult to understand potential mechanisms of sulfate inhibition and complicate the interpretation of bioremediation field data. In order to elucidate interactions between sulfate reduction and reductive dechlorination, this study systematically evaluated the effects of different concentrations of sulfate and sulfide on reductive dechlorination by isolates, constructed consortia, and enrichments containing Dehalococcoides sp. This study provides a more fundamental understanding of the competition mechanisms between reductive dechlorination by Dehalococcoides mccartyi and sulfate reduction during the bioremediation process. It also provides insights on the significance of sulfate concentrations on reductive dechlorination under electron donor/acceptor-limiting conditions during in situ bioremediation applications. For example, at a trichloroethene-contaminated site with a high sulfate concentration, proper slow-releasing electron donors can be selected to generate an electron donor-limiting environment that favors reductive dechlorination and minimizes the sulfide inhibition effect.

scholarly journals A Microcosm Treatability Study for Evaluating Wood Mulch-Based Amendments as Electron Donors for Trichloroethene (TCE) Reductive Dechlorination

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1949
Author(s):  
Edoardo Masut ◽  
Alessandro Battaglia ◽  
Luca Ferioli ◽  
Anna Legnani ◽  
Carolina Cruz Viggi ◽  
...  
Keyword(s):  
Electron Donor ◽  
Environmental Sustainability ◽  
Reductive Dechlorination ◽  
Environmental Remediation ◽  
Low Cost ◽  
Chlorinated Solvents ◽  
Electron Donors ◽  
Chlorinated Ethenes ◽  
Dehalococcoides Mccartyi ◽  
Wood Mulch

In this study, wood mulch-based amendments were tested in a bench-scale microcosm experiment in order to assess the treatability of saturated soils and groundwater from an industrial site contaminated by chlorinated ethenes. Wood mulch was tested alone as the only electron donor in order to assess its potential for stimulating the biological reductive dechlorination. It was also tested in combination with millimetric iron filings in order to assess the ability of the additive to accelerate/improve the bioremediation process. The efficacy of the selected amendments was compared with that of unamended control microcosms. The results demonstrated that wood mulch is an effective natural and low-cost electron donor to stimulate the complete reductive dechlorination of chlorinated solvents to ethene. Being a side-product of the wood industry, mulch can be used in environmental remediation, an approach which perfectly fits the principles of circular economy and addresses the compelling needs of a sustainable and low environmental impact remediation. The efficacy of mulch was further improved by the co-presence of iron filings, which accelerated the conversion of vinyl chloride into the ethene by increasing the H2 availability rather than by catalyzing the direct abiotic dechlorination of contaminants. Chemical analyses were corroborated by biomolecular assays, which confirmed the stimulatory effect of the selected amendments on the abundance of Dehalococcoides mccartyi and related reductive dehalogenase genes. Overall, this paper further highlights the application potential and environmental sustainability of wood mulch-based amendments as low-cost electron donors for the biological treatment of chlorinated ethenes.

scholarly journals Unexpected Specificity of Interspecies Cobamide Transfer from Geobacter spp. to Organohalide-Respiring Dehalococcoides mccartyi Strains

2012 ◽  
Vol 78 (18) ◽  
pp. 6630-6636 ◽  
Author(s):  
Jun Yan ◽  
Kirsti M. Ritalahti ◽  
Darlene D. Wagner ◽  
Frank E. Löffler
Keyword(s):  
Reductive Dechlorination ◽  
De Novo ◽  
Synthetic Medium ◽  
Geobacter Sulfurreducens ◽  
Rrna Gene ◽  
Content Type ◽  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Gene Copies ◽  
Pure Cultures

ABSTRACTDehalococcoides mccartyistrains conserve energy from reductive dechlorination reactions catalyzed by corrinoid-dependent reductive dehalogenase enzyme systems.Dehalococcoideslacks the ability forde novocorrinoid synthesis, and pure cultures require the addition of cyanocobalamin (vitamin B12) for growth. In contrast,Geobacter lovleyi, which dechlorinates tetrachloroethene tocis-1,2-dichloroethene (cis-DCE), and the nondechlorinating speciesGeobacter sulfurreducenshave complete sets of cobamide biosynthesis genes and produced 12.9 ± 2.4 and 24.2 ± 5.8 ng of extracellular cobamide per liter of culture suspension, respectively, during growth with acetate and fumarate in a completely synthetic medium.G. lovleyi-D. mccartyistrain BAV1 or strain FL2 cocultures provided evidence for interspecies corrinoid transfer, andcis-DCE was dechlorinated to vinyl chloride and ethene concomitant withDehalococcoidesgrowth. In contrast, negligible increase inDehalococcoides16S rRNA gene copies and insignificant dechlorination occurred inG. sulfurreducens-D. mccartyistrain BAV1 or strain FL2 cocultures. Apparently,G. lovleyiproduces a cobamide that complementsDehalococcoides' nutritional requirements, whereasG. sulfurreducensdoes not. Interestingly,Dehalococcoidesdechlorination activity and growth could be restored inG. sulfurreducens-Dehalococcoidescocultures by adding 10 μM 5′,6′-dimethylbenzimidazole. Observations made with theG. sulfurreducens-Dehalococcoidescocultures suggest that the exchange of the lower ligand generated a cobalamin, which supportedDehalococcoidesactivity. These findings have implications forin situbioremediation and suggest that the corrinoid metabolism ofDehalococcoidesmust be understood to faithfully predict, and possibly enhance, reductive dechlorination activities.

scholarly journals Effects of Deletion of Genes Encoding Fe-Only Hydrogenase of Desulfovibrio vulgaris Hildenborough on Hydrogen and Lactate Metabolism

2002 ◽  
Vol 184 (3) ◽  
pp. 679-686 ◽  
Author(s):  
Brant K. J. Pohorelic ◽  
Johanna K. Voordouw ◽  
Elisabeth Lojou ◽  
Alain Dolla ◽  
Jens Harder ◽  
...  
Keyword(s):  
Sulfate Reduction ◽  
Electron Donor ◽  
Type Strain ◽  
Wild Type Strain ◽  
Physiological Role ◽  
Hydrogen Uptake ◽  
Desulfovibrio Vulgaris ◽  
Lactate Metabolism ◽  
Wild Type ◽  
Genes Encoding

ABSTRACT The physiological properties of a hyd mutant of Desulfovibrio vulgaris Hildenborough, lacking periplasmic Fe-only hydrogenase, have been compared with those of the wild-type strain. Fe-only hydrogenase is the main hydrogenase of D. vulgaris Hildenborough, which also has periplasmic NiFe- and NiFeSe-hydrogenases. The hyd mutant grew less well than the wild-type strain in media with sulfate as the electron acceptor and H2 as the sole electron donor, especially at a high sulfate concentration. Although the hyd mutation had little effect on growth with lactate as the electron donor for sulfate reduction when H2 was also present, growth in lactate- and sulfate-containing media lacking H2 was less efficient. The hyd mutant produced, transiently, significant amounts of H2 under these conditions, which were eventually all used for sulfate reduction. The results do not confirm the essential role proposed elsewhere for Fe-only hydrogenase as a hydrogen-producing enzyme in lactate metabolism (W. A. M. van den Berg, W. M. A. M. van Dongen, and C. Veeger, J. Bacteriol. 173:3688–3694, 1991). This role is more likely played by a membrane-bound, cytoplasmic Ech-hydrogenase homolog, which is indicated by the D. vulgaris genome sequence. The physiological role of periplasmic Fe-only hydrogenase is hydrogen uptake, both when hydrogen is and when lactate is the electron donor for sulfate reduction.

scholarly journals Hydrogen Does Not Appear To Be a Major Electron Donor for Symbiosis with the Deep-Sea Hydrothermal Vent Tubeworm Riftia pachyptila

2019 ◽  
Vol 86 (1) ◽  
Author(s):  
Jessica H. Mitchell ◽  
Juliana M. Leonard ◽  
Jennifer Delaney ◽  
Peter R. Girguis ◽  
Kathleen M. Scott
Keyword(s):  
High Pressure ◽  
Electron Donor ◽  
Deep Sea ◽  
Symbiotic Association ◽  
Omics Data ◽  
Riftia Pachyptila ◽  
Free Living ◽  
Content Type ◽  
Genes Encoding ◽  
Chemolithoautotrophic Bacteria

ABSTRACT Use of hydrogen gas (H2) as an electron donor is common among free-living chemolithotrophic microorganisms. Given the presence of this dissolved gas at deep-sea hydrothermal vents, it has been suggested that it may also be a major electron donor for the free-living and symbiotic chemolithoautotrophic bacteria that are the primary producers at these sites. Giant Riftia pachyptila siboglinid tubeworms and their symbiotic bacteria (“Candidatus Endoriftia persephone”) dominate many vents in the Eastern Pacific, and their use of sulfide as a major electron donor has been documented. Genes encoding hydrogenase are present in the “Ca. Endoriftia persephone” genome, and proteome data suggest that these genes are expressed. In this study, high-pressure respirometry of intact R. pachyptila and incubations of trophosome homogenate were used to determine whether this symbiotic association could also use H2 as a major electron donor. Measured rates of H2 uptake by intact R. pachyptila in high-pressure respirometers were similar to rates measured in the absence of tubeworms. Oxygen uptake rates in the presence of H2 were always markedly lower than those measured in the presence of sulfide, as was the incorporation of 13C-labeled dissolved inorganic carbon. Carbon fixation by trophosome homogenate was not stimulated by H2, nor was hydrogenase activity detectable in these samples. Though genes encoding [NiFe] group 1e and [NiFe] group 3b hydrogenases are present in the genome and transcribed, it does not appear that H2 is a major electron donor for this system, and it may instead play a role in intracellular redox homeostasis. IMPORTANCE Despite the presence of hydrogenase genes, transcripts, and proteins in the “Ca. Endoriftia persephone” genome, transcriptome, and proteome, it does not appear that R. pachyptila can use H2 as a major electron donor. For many uncultivable microorganisms, omic analyses are the basis for inferences about their activities in situ. However, as is apparent from the study reported here, there are dangers in extrapolating from omics data to function, and it is essential, whenever possible, to verify functions predicted from omics data with physiological and biochemical measurements.

scholarly journals Complete Genome Sequence of Dehalococcoides mccartyi Strain FL2, a Trichloroethene-Respiring Anaerobe Isolated from Pristine Freshwater Sediment

2019 ◽  
Vol 8 (33) ◽  
Author(s):  
Jun Yan ◽  
Yi Yang ◽  
Xiuying Li ◽  
Frank E. Löffler
Keyword(s):  
Complete Genome Sequence ◽  
Reductive Dechlorination ◽  
Complete Genome ◽  
Hydrogen Oxidation ◽  
Protein Coding ◽  
Coding Sequences ◽  
Content Type ◽  
Reductive Dehalogenase ◽  
Dehalococcoides Mccartyi ◽  
Reductive Dehalogenase Genes

Dehalococcoides mccartyi strain FL2 couples growth to hydrogen oxidation and reductive dechlorination of trichloroethene and cis- and trans-1,2-dichloroethenes. Strain FL2 has a 1.42-Mb genome with a G+C content of 47.0% and carries 1,465 protein-coding sequences, including 24 reductive dehalogenase genes.

scholarly journals Draft Genome Sequence of Desulfofundulus thermobenzoicus subsp. thermosyntrophicus DSM 14055, a Moderately Thermophilic Sulfate Reducer

2020 ◽  
Vol 9 (3) ◽  
Author(s):  
Emma Bertran ◽  
Lewis M. Ward ◽  
David T. Johnston
Keyword(s):  
Sulfate Reduction ◽  
Genome Sequence ◽  
Draft Genome ◽  
Draft Genome Sequence ◽  
Sulfate Reducer ◽  
Content Type ◽  
Moderately Thermophilic ◽  
Microbial Sulfate Reduction

Here, we describe the genome of Desulfofundulus thermobenzoicus subsp. thermosyntrophicus DSM 14055, a member of the Clostridiales that is capable of sulfate reduction coupled to the oxidation of propionate, lactate, pyruvate, and H2/CO2. This genome expands our understanding of microbial sulfate reduction (MSR) in anaerobic methanogenic environments.

scholarly journals Acetylene-Fueled Trichloroethene Reductive Dechlorination in a Groundwater Enrichment Culture

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sara Gushgari-Doyle ◽  
Ronald S. Oremland ◽  
Ray Keren ◽  
Shaun M. Baesman ◽  
Denise M. Akob ◽  
...  
Keyword(s):  
Microbial Community ◽  
Reductive Dechlorination ◽  
Enrichment Culture ◽  
The United States ◽  
Degradation Pathway ◽  
Content Type ◽  
Dehalococcoides Mccartyi ◽  
Abiotic Degradation ◽  
Laboratory Microcosm ◽  
Microcosm Studies

ABSTRACT In aquifers, acetylene (C2H2) is a product of abiotic degradation of trichloroethene (TCE) catalyzed by in situ minerals. C2H2 can, in turn, inhibit multiple microbial processes including TCE dechlorination and metabolisms that commonly support dechlorination, in addition to supporting the growth of acetylenotrophic microorganisms. Previously, C2H2 was shown to support TCE reductive dechlorination in synthetic, laboratory-constructed cocultures containing the acetylenotroph Pelobacter sp. strain SFB93 and Dehalococcoides mccartyi strain 195 or strain BAV1. In this study, we demonstrate TCE and perchloroethene (PCE) reductive dechlorination by a microbial community enriched from contaminated groundwater and amended with C2H2 as the sole electron donor and organic carbon source. The metagenome of the stable, enriched community was analyzed to elucidate putative community functions. A novel anaerobic acetylenotroph in the phylum Actinobacteria was identified using metagenomic analysis. These results demonstrate that the coupling of acetylenotrophy and reductive dechlorination can occur in the environment with native bacteria and broaden our understanding of biotransformation at contaminated sites containing both TCE and C2H2. IMPORTANCE Understanding the complex metabolisms of microbial communities in contaminated groundwaters is a challenge. PCE and TCE are among the most common groundwater contaminants in the United States that, when exposed to certain minerals, exhibit a unique abiotic degradation pathway in which C2H2 is a product. C2H2 can act as both an inhibitor of TCE dechlorination and of supporting metabolisms and an energy source for acetylenotrophic bacteria. Here, we combine laboratory microcosm studies with computational approaches to enrich and characterize an environmental microbial community that couples two uncommon metabolisms, demonstrating unique metabolic interactions only yet reported in synthetic, laboratory-constructed settings. Using this comprehensive approach, we have identified the first reported anaerobic acetylenotroph in the phylum Actinobacteria, demonstrating the yet-undescribed diversity of this metabolism that is widely considered to be uncommon.

scholarly journals Rex (Encoded by DVU_0916) in Desulfovibrio vulgaris Hildenborough Is a Repressor of Sulfate Adenylyl Transferase and Is Regulated by NADH

2014 ◽  
Vol 197 (1) ◽  
pp. 29-39 ◽  
Author(s):  
G. A. Christensen ◽  
G. M. Zane ◽  
A. E. Kazakov ◽  
X. Li ◽  
D. A. Rodionov ◽  
...  
Keyword(s):  
Binding Site ◽  
Sulfate Reduction ◽  
Transcriptional Start Site ◽  
Redox Status ◽  
Desulfovibrio Vulgaris ◽  
Dissimilatory Sulfate Reduction ◽  
Content Type ◽  
Sulfate Reducing ◽  
Genes Encoding

Although the enzymes for dissimilatory sulfate reduction by microbes have been studied, the mechanisms for transcriptional regulation of the encoding genes remain unknown. In a number of bacteria the transcriptional regulator Rex has been shown to play a key role as a repressor of genes producing proteins involved in energy conversion. In the model sulfate-reducing microbeDesulfovibrio vulgarisHildenborough, the gene DVU_0916 was observed to resemble other known Rex proteins. Therefore, the DVU_0916 protein has been predicted to be a transcriptional repressor of genes encoding proteins that function in the process of sulfate reduction inD. vulgarisHildenborough. Examination of the deduced DVU_0916 protein identified two domains, one a winged helix DNA-binding domain common for transcription factors, and the other a Rossman fold that could potentially interact with pyridine nucleotides. A deletion of the putativerexgene was made inD. vulgarisHildenborough, and transcript expression studies ofsat, encoding sulfate adenylyl transferase, showed increased levels in theD. vulgarisHildenborough Rex (RexDvH) mutant relative to the parental strain. The RexDvH-binding site upstream ofsatwas identified, confirming RexDvHto be a repressor ofsat. We establishedin vitrothat the presence of elevated NADH disrupted the interaction between RexDvHand DNA. Examination of the 5′ transcriptional start site for thesatmRNA revealed two unique start sites, one for respiring cells that correlated with the RexDvH-binding site and a second for fermenting cells. Collectively, these data support the role of RexDvHas a transcription repressor forsatthat senses the redox status of the cell.

scholarly journals Tetrachloroethene Dehalorespiration and Growth of Desulfitobacterium frappieri TCE1 in Strict Dependence on the Activity of Desulfovibrio fructosivorans

2002 ◽  
Vol 68 (2) ◽  
pp. 642-649 ◽  
Author(s):  
Oliver Drzyzga ◽  
Jan C. Gottschal
Keyword(s):  
Continuous Culture ◽  
Population Size ◽  
Sulfate Reduction ◽  
Gas Phase ◽  
Electron Donor ◽  
Hydrogen Transfer ◽  
Sulfate Reducer ◽  
Interspecies Hydrogen Transfer ◽  
Sulfate Reducing ◽  
First Time

ABSTRACT Tetrachloroethene (PCE) dehalorespiration was investigated in a continuous coculture of the sulfate-reducing bacterium Desulfovibrio fructosivorans and the dehalorespiring Desulfitobacterium frappieri TCE1 at different sulfate concentrations and in the absence of sulfate. Fructose (2.5 mM) was the single electron donor, which could be used only by the sulfate reducer. With 2.5 mM sulfate, the dehalogenating strain was outnumbered by the sulfate-reducing bacterium, sulfate reduction was the dominating process, and only trace amounts of PCE were dehalogenated by strain TCE1. With 1 mM sulfate in the medium, complete sulfate reduction and complete PCE dehalogenation to cis-dichloroethene (cis-DCE) occurred. In the absence of sulfate, PCE was also completely dehalogenated to cis-DCE, and the population size of strain TCE1 increased significantly. The results presented here describe for the first time dehalogenation of PCE by a dehalorespiring anaerobe in strict dependence on the activity of a sulfate-reducing bacterium with a substrate that is exclusively used by the sulfate reducer. This interaction was studied under strictly controlled and quantifiable conditions in continuous culture and shown to depend on interspecies hydrogen transfer under sulfate-depleted conditions. Interspecies hydrogen transfer was demonstrated by direct H2 measurements of the gas phase and by the production of methane after the addition of a third organism, Methanobacterium formicicum.

scholarly journals Genome Reduction and Secondary Metabolism of the Marine Sponge-Associated Cyanobacterium Leptothoe

Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 298
Author(s):  
Despoina Konstantinou ◽  
Rafael V. Popin ◽  
David P. Fewer ◽  
Kaarina Sivonen ◽  
Spyros Gkelis
Keyword(s):  
Natural Products ◽  
Microbial Communities ◽  
Genomic Analysis ◽  
Gene Clusters ◽  
Marine Sponges ◽  
Genome Reduction ◽  
Extracellular Polysaccharides ◽  
Comparative Genomic ◽  
Symbiotic Relationships ◽  
Genes Encoding

Sponges form symbiotic relationships with diverse and abundant microbial communities. Cyanobacteria are among the most important members of the microbial communities that are associated with sponges. Here, we performed a genus-wide comparative genomic analysis of the newly described marine benthic cyanobacterial genus Leptothoe (Synechococcales). We obtained draft genomes from Le. kymatousa TAU-MAC 1615 and Le. spongobia TAU-MAC 1115, isolated from marine sponges. We identified five additional Leptothoe genomes, host-associated or free-living, using a phylogenomic approach, and the comparison of all genomes showed that the sponge-associated strains display features of a symbiotic lifestyle. Le. kymatousa and Le. spongobia have undergone genome reduction; they harbored considerably fewer genes encoding for (i) cofactors, vitamins, prosthetic groups, pigments, proteins, and amino acid biosynthesis; (ii) DNA repair; (iii) antioxidant enzymes; and (iv) biosynthesis of capsular and extracellular polysaccharides. They have also lost several genes related to chemotaxis and motility. Eukaryotic-like proteins, such as ankyrin repeats, playing important roles in sponge-symbiont interactions, were identified in sponge-associated Leptothoe genomes. The sponge-associated Leptothoe stains harbored biosynthetic gene clusters encoding novel natural products despite genome reduction. Comparisons of the biosynthetic capacities of Leptothoe with chemically rich cyanobacteria revealed that Leptothoe is another promising marine cyanobacterium for the biosynthesis of novel natural products.

Sign in / Sign up

Export Citation Format

Share Document