Genome Sequence of the Mercury-Methylating and Pleomorphic Desulfovibrio africanus Strain Walvis Bay

Brown, Steven D.; Wall, Judy D.; Kucken, Amy M.; Gilmour, Cynthia C.; Podar, Mircea; Brandt, Craig C.; Teshima, Hazuki; Detter, John C.; Han, Cliff; Land, Miriam; Lucas, Susan; Han, James; Pennacchio, Len A.; Nolan, Matt; Pitluck, Sam; Woyke, Tanja; Goodwin, Lynne; Palumbo, Anthony V.; Elias, Dwayne A.

doi:10.1128/jb.05223-11

Cited by 14 publications

(12 citation statements)

References 19 publications

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“…The PCS genome had a G+C content of 61.2%, which is similar to the 61.4% G+C content reported for strain Walvis Bay (4). Strain PCS shows 95% average nucleotide identity to strain Walvis Bay when the two genome sequences are compared using the JSpecies program (22).…”

Section: Genome Announcementsupporting

confidence: 78%

“…The isolated strain was Gram negative, motile, nonsporulating, and 99% similar by 16S rRNA gene sequencing to Desulfovibrio africanus subsp. uniflagellum (GenBank accession number EU659693) and D. africanus strain Walvis Bay (CP003221.1) (4), which is consistent with the species definition (5). D. africanus strains, including PCS, have different morphotypes associated with a cell cycle (6–10), and PCS incompletely oxidizes lactate, accumulating acetate as an end product.…”

Section: Genome Announcementsupporting

confidence: 77%

“…The capability to produce MeHg is found only in a subset of SRB and Fe(III)-reducing bacteria (IRB) (11–16). A 4.2-Mb complete genome sequence for D. africanus strain Walvis Bay (4, 17), which produces MeHg, has been reported (10, 12). Recently, genetic studies have shown that a two-gene cluster encoding a putative corrinoid-containing CO dehydrogenase/acetyl coenzyme A (acetyl-CoA) synthase, HgcA, and a 2[4Fe-4S] ferredoxin, HgcB, is required to produce MeHg in SRB and IRB (18).…”

Section: Genome Announcementmentioning

confidence: 99%

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Draft Genome Sequence for Desulfovibrio africanus Strain PCS

et al. 2013

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Section: Genome Announcementsupporting

confidence: 78%

Section: Genome Announcementsupporting

confidence: 77%

Section: Genome Announcementmentioning

confidence: 99%

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Draft Genome Sequence for Desulfovibrio africanus Strain PCS

et al. 2013

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“…Recent studies have shown that most of the commonly studied Desulfovibrio strains align into a clade with few Hg methylators, while most of the Hg methylating strains fall into the halophiles group 20 . The finished genomes for Desulfovibrio strain ND132, Desulfovibrio africanus strain Walvis Bay and Desulfovibrio africanus strain PCS are the first complete genomes for the strains that generate MeHg 38 39 40 . This will aid in to our studies with comparison of full genomes of known Hg methylators identified in DWW and comparative metagenomics of Hg contaminated ecosystems.…”

Section: Resultsmentioning

confidence: 99%

Geochemical influences and mercury methylation of a dental wastewater microbiome

Rani

Rockne

Drummond

et al. 2015

Sci Rep

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The microbiome of dental clinic wastewater and its impact on mercury methylation remains largely unknown. Waste generated during dental procedures enters the sewer system and contributes a significant fraction of the total mercury (tHg) and methyl mercury (MeHg) load to wastewater treatment facilities. Investigating the influence of geochemical factors and microbiome structure is a critical step linking the methylating microorganisms in dental wastewater (DWW) ecosystems. DWW samples from a dental clinic were collected over eight weeks and analyzed for geochemical parameters, tHg, MeHg and bacterio-toxic heavy metals. We employed bacterial fingerprinting and pyrosequencing for microbiome analysis. High concentrations of tHg, MeHg and heavy metals were detected in DWW. The microbiome was dominated by Proteobacteria, Actinobacteria, Bacteroidetes, Chloroflexi and many unclassified bacteria. Significant correlations were found between the bacterial community, Hg levels and geochemical factors including pH and the predicted total amount (not fraction) of neutral Hg-sulfide species. The most prevalent known methylators included Desulfobulbus propionicus, Desulfovibrio desulfuricans, Desulfovibrio magneticus and Geobacter sulfurreducens. This study is the first to investigate the impact of high loads of Hg, MeHg and other heavy metals on the dental clinic wastewater microbiome, and illuminates the role of many known and unknown sulfatereducing bacteria in Hg methylation.Methyl mercury (MeHg) is a potent neurotoxin that causes significant risk to humans 1-3 and other top predators through the process of bio-magnifications 4,5 . Atmospheric emissions of Hg can be transported over long distances and impact surface waters through deposition and subsequent transformation to the methyl form 6,7 . A comparatively less investigated pathway of MeHg input to surface waters is via direct dental wastewater (DWW) discharge. Waste material generated from dental offices during dental procedures enters the sewer system and represent a significant fraction of Hg load to wastewater treatment facilities [8][9][10][11][12][13] . Approximately 50% of mercury entering municipal wastewater treatment plants (WWTPs) comes from dental amalgam waste from discharges totaling 3.7 tons per year in the USA 14 .Mercury methylation is a natural process that converts Hg (II) to the bio-accumulative toxin MeHg, thought to be primarily mediated by sulfate-reducing and iron-reducing bacteria (SRB and FeRB respectively) [15][16][17][18][19] . However, not all SRB and FeRB strains are able to produce MeHg, and to date only few methylating bacteria have been positively identified and sequenced [20][21][22] . Most SRB that have been confirmed to methylate Hg are in the orders Desulfovibrionales and Desulfobacterales [23][24][25][26][27] . In addition, several species of Geobacter and Desulfuromonas palmitatis SDBY1 produce MeHg 18,19,28 . Mercury methylation outside the class Deltaproteobacteria was thought to be limited to Gammaproteobacteria and Firmicutes...

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“…Significant advances in our knowledge of the microbial Hg methylation process have been made over the last two decades (e.g., Gilmour and Henry, 1991 ; Choi and Bartha, 1993 ; Choi et al, 1994a , b ; Ekstrom et al, 2003 ; Schaefer and Morel, 2009 ; Brown et al, 2011a , b ; Gilmour et al, 2011 ; Parks et al, 2013 ). Still, major gaps persist in our understanding of the geochemical forms of inorganic Hg available for biomethylation (Benoit et al, 2003 ; Jonsson et al, 2012 ; Hsu-Kim et al, 2013 ), the biochemical pathways involved (Landner, 1971 ; Choi et al, 1994b ; Poulain and Barkay, 2013 ), and the mechanism for uptake of Hg by methylating microbes (Benoit et al, 1999 , 2001a ; Schaefer and Morel, 2009 ; Bridou et al, 2011 ; Schaefer et al, 2011 , 2014 ; Pedrero et al, 2012 ).…”

Section: Introductionmentioning

confidence: 99%

The Effect of Natural Organic Matter on Mercury Methylation by Desulfobulbus propionicus 1pr3

et al. 2015

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Methylation of tracer and ambient mercury (200Hg and 202Hg, respectively) equilibrated with four different natural organic matter (NOM) isolates was investigated in vivo using the Hg-methylating sulfate-reducing bacterium Desulfobulbus propionicus 1pr3. Desulfobulbus cultures grown fermentatively with environmentally representative concentrations of dissolved NOM isolates, Hg[II], and HS− were assayed for absolute methylmercury (MeHg) concentration and conversion of Hg(II) to MeHg relative to total unfiltered Hg(II). Results showed the 200Hg tracer was methylated more efficiently in the presence of hydrophobic NOM isolates than in the presence of transphilic NOM, or in the absence of NOM. Different NOM isolates were associated with variable methylation efficiencies for either the 202Hg tracer or ambient 200Hg. One hydrophobic NOM, F1 HpoA derived from dissolved organic matter from the Florida Everglades, was equilibrated for different times with Hg tracer, which resulted in different methylation rates. A 5 day equilibration with F1 HpoA resulted in more MeHg production than either the 4 h or 30 day equilibration periods, suggesting a time dependence for NOM-enhanced Hg bioavailability for methylation.

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Genome Sequence of the Mercury-Methylating and Pleomorphic Desulfovibrio africanus Strain Walvis Bay

Cited by 14 publications

References 19 publications

Draft Genome Sequence for Desulfovibrio africanus Strain PCS

Draft Genome Sequence for Desulfovibrio africanus Strain PCS

Geochemical influences and mercury methylation of a dental wastewater microbiome

The Effect of Natural Organic Matter on Mercury Methylation by Desulfobulbus propionicus 1pr3

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