title: Syntrophs dominate sequences associated with the mercury methylation-related gene hgcA in the water conservation areas of the Florida Everglades.
abstract: The mechanisms and rates of mercury methylation in the Florida Everglades are of great concern because of potential adverse impacts on human and wildlife health through mercury accumulation in aquatic food webs. We developed a new PCR primer set targeting hgcA, a gene encoding a corrinoid protein essential for Hg methylation across broad phylogenetic boundaries, and used this primer set to study the distribution of hgcA sequences in soils collected from three sites along a gradient in sulfate and nutrient concentrations in the northern Everglades. The sequences obtained were distributed in diverse phyla, including Proteobacteria, Chloroflexi, Firmicutes, and Methanomicrobia; however, hgcA clone libraries from all sites were dominated by sequences clustering within the order Syntrophobacterales of the Deltaproteobacteria (49 to 65% of total sequences). dsrB mRNA sequences, representing active sulfate-reducing prokaryotes at the time of sampling, obtained from these sites were also dominated by Syntrophobacterales (75 to 89%). Laboratory incubations with soils taken from the site low in sulfate concentrations also suggested that Hg methylation activities were primarily mediated by members of the order Syntrophobacterales, with some contribution by methanogens, Chloroflexi, iron-reducing Geobacter, and non-sulfate-reducing Firmicutes inhabiting the sites. This suggests that prokaryotes distributed within clades defined by syntrophs are the predominant group controlling methylation of Hg in low-sulfate areas of the Everglades. Any strategy for managing mercury methylation in the Everglades should consider that net mercury methylation is not limited to the action of sulfate reduction.
authors.affiliation: Soil and Water Science Department, University of Florida, Gainesville, Florida, USA.
authors.forename: Hee-Sung
authors.initials: HS
authors.lastname: Bae
authors.affiliation: DB Environmental Inc., Rockledge, Florida, USA.
authors.forename: Forrest E
authors.initials: FE
authors.lastname: Dierberg
authors.affiliation: Soil and Water Science Department, University of Florida, Gainesville, Florida, USA aogram@ufl.edu.
authors.forename: Andrew
authors.initials: A
authors.lastname: Ogram
mesh_terms: D044822:Biodiversity; D041862:Chloroflexi / Q000235:genetics / Q000378:metabolism; D019915:DNA Primase; D020564:Deltaproteobacteria / Q000235:genetics* / Q000378:metabolism; D017753:Ecosystem; D004784:Environmental Monitoring; D005431:Florida; D005798:Genes, Bacterial; D045302:Geobacter / Q000235:genetics; D008628:Mercury / Q000378:metabolism*; D008745:Methylation; D008767:Methylmercury Compounds / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D012988:Soil Microbiology; D013431:Sulfates
chemical_list: D008767:Methylmercury Compounds; D013431:Sulfates; D019915:DNA Primase; D008628:Mercury
references.citation: FEMS Microbiol Lett. 2013 Jun;343(2):101-4
references.pmid: 23600617
references.citation: Crit Rev Clin Lab Sci. 1997;34(4):369-403
references.pmid: 9288445
references.citation: Science. 2013 Mar 15;339(6125):1332-5
references.pmid: 23393089
references.citation: Environ Sci Technol. 2010 May 15;44(10):3752-7
references.pmid: 20429556
references.citation: Appl Environ Microbiol. 2006 Mar;72(3):2080-91
references.pmid: 16517657
references.citation: Environ Microbiol Rep. 2014 Oct;6(5):441-7
references.pmid: 25646534
references.citation: Appl Environ Microbiol. 2006 Apr;72(4):2400-6
references.pmid: 16597937
references.citation: Front Microbiol. 2011 May 02;2:81
references.pmid: 21734907
references.citation: Appl Environ Microbiol. 2006 Dec;72(12):7919-21
references.pmid: 17056699
references.citation: Environ Sci Technol. 2013 Oct 15;47(20):11810-20
references.pmid: 24024607
references.citation: Appl Environ Microbiol. 2004 Jun;70(6):3475-84
references.pmid: 15184146
references.citation: Appl Environ Microbiol. 2002 Dec;68(12):6129-37
references.pmid: 12450837
references.citation: Ann N Y Acad Sci. 2008 Mar;1125:58-72
references.pmid: 18378587
references.citation: FEMS Microbiol Ecol. 2000 Jan 1;31(1):1-9
references.pmid: 10620713
references.citation: Trends Mol Med. 2002 Jun;8(6):257-60
references.pmid: 12067606
references.citation: Appl Environ Microbiol. 2009 Dec;75(23):7537-41
references.pmid: 19801464
references.citation: Environ Sci Technol. 2009 Jun 15;43(12):4361-6
references.pmid: 19603647
references.citation: Appl Environ Microbiol. 2002 Aug;68(8):3673-82
references.pmid: 12147459
references.citation: Appl Environ Microbiol. 1991 Dec;57(12):3438-49
references.pmid: 1785921
references.citation: Appl Environ Microbiol. 2013 Oct;79(20):6325-30
references.pmid: 23934484
references.citation: J Environ Qual. 2001 Jul-Aug;30(4):1438-46
references.pmid: 11476523
references.citation: ISME J. 2010 Jan;4(1):17-27
references.pmid: 19710709
references.citation: Appl Environ Microbiol. 1998 Mar;64(3):1013-7
references.pmid: 16349509
references.citation: Appl Environ Microbiol. 2004 Nov;70(11):6559-68
references.pmid: 15528519
references.citation: Mol Biol Evol. 2011 Oct;28(10):2731-9
references.pmid: 21546353
references.citation: Appl Environ Microbiol. 2009 Jul;75(13):4435-42
references.pmid: 19447957
references.citation: Appl Environ Microbiol. 2007 Apr;73(7):2093-100
references.pmid: 17308191
references.citation: Syst Appl Microbiol. 1999 Dec;22(4):559-64
references.pmid: 10794144
references.citation: Appl Environ Microbiol. 2000 Jun;66(6):2430-7
references.pmid: 10831421
references.citation: Nat Rev Microbiol. 2009 Aug;7(8):568-77
references.pmid: 19609258
references.citation: Appl Environ Microbiol. 2006 Jan;72(1):457-64
references.pmid: 16391078
references.citation: Appl Environ Microbiol. 2005 Dec;71(12):8228-35
references.pmid: 16332807
references.citation: Appl Environ Microbiol. 2007 Jan;73(2):594-604
references.pmid: 17098925
references.citation: FEMS Microbiol Ecol. 2011 May;76(2):289-300
references.pmid: 21223338
references.citation: Ambio. 2007 Feb;36(1):3-11
references.pmid: 17408186
references.citation: Environ Sci Technol. 2011 Sep 15;45(18):7693-700
references.pmid: 21875053
references.citation: Nucleic Acids Res. 1997 Dec 15;25(24):4876-82
references.pmid: 9396791
references.citation: Environ Sci Technol. 2013 Mar 19;47(6):2441-56
references.pmid: 23384298
references.citation: Inorg Chem. 2014 Jan 21;53(2):772-7
references.pmid: 24377658
references.citation: Appl Environ Microbiol. 2005 May;71(5):2695-704
references.pmid: 15870361