title: Investigation of mercury methylation pathways in biofilm versus planktonic cultures of Desulfovibrio desulfuricans.
abstract: Biofilms can methylate mercury (Hg) at higher rates than unattached bacteria and are increasingly recognized as important Hg methylation sites in the environment. Our previous study showed that methylation rates in biofilm cultures were up to 1 order of magnitude greater than those in planktonic cultures of a sulfate-reducing bacterium. To probe whether the differential Hg methylation rates resulted from metabolic differences between these two cultures, Hg methylation assays following molybdate or chloroform inhibition (a specific inhibitor of the acetyl-CoA pathway) were conducted on biofilm and planktonic cultures of Desulfovibrio desulfuricans strains M8 and ND132. Molybdate was as effective in inhibiting Hg methylation as well as growth in both planktonic and biofilm cultures. The addition of chloroform only impacted Hg methylation in biofilm cultures, suggesting that different pathways are used for methylation in biofilm compared to planktonic cultures. To investigate this further, expression of the cooS gene, which encodes for carbon monoxide dehydrogenase, a key enzyme in the acetyl-CoA pathway, was compared in biofilm and planktonic cultures of ND132. Biofilm cultures showed up to 4 times higher expression of cooS than planktonic cultures. On the basis of these results, the acetyl-CoA pathway appears to play an important role in methylation in biofilm cultures of this organism, possibly by supplying the methyl group to Hg methylating enzymes; methylation in planktonic cultures appears to be independent of this pathway. This observation has important implications, particularly in developing reliable models to predict Hg methylation rates in different environments and perhaps eventually in being able to control this undesirable chemical transformation.
authors: Department of Civil and Environmental Engineering, University of California at Los Angeles, Box 951593, Los Angeles, California 90095-1593, United States.
authors: Tiffany Y
authors: TY
authors: Lin
authors: Rita A
authors: RA
authors: Kampalath
authors: Chu-Ching
authors: CC
authors: Lin
authors: Ming
authors: M
authors: Zhang
authors: Karina
authors: K
authors: Chavarria
authors: Jessica
authors: J
authors: Lacson
authors: Jennifer A
authors: JA
authors: Jay
mesh_terms: D000105:Acetyl Coenzyme A / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002725:Chloroform / Q000494:pharmacology; D045285:Desulfovibrio desulfuricans / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D008628:Mercury / Q000378:metabolism*; D008745:Methylation; D008982:Molybdenum / Q000494:pharmacology; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D010933:Plankton / Q000378:metabolism
chemical_list: D009097:Multienzyme Complexes; C044659:molybdate; D000105:Acetyl Coenzyme A; D002725:Chloroform; D008982:Molybdenum; D000445:Aldehyde Oxidoreductases; C019823:carbon monoxide dehydrogenase; D008628:Mercury
references: Genome Biol. 2002 Jun 18;3(7):RESEARCH0034
references: 12184808
references: Environ Health Perspect. 1991 Dec;96:159-66
references: 1820259
references: Appl Environ Microbiol. 2011 Jun;77(12):3938-51
references: 21515733
references: Environ Sci Technol. 2008 Jan 1;42(1):93-9
references: 18350881
references: Appl Environ Microbiol. 1993 Jan;59(1):290-5
references: 8439155
references: Appl Environ Microbiol. 2006 Dec;72(12):7919-21
references: 17056699
references: J Bacteriol. 2003 Mar;185(5):1485-91
references: 12591863
references: Environ Sci Technol. 2001 Jun 15;35(12):2491-6
references: 11432553
references: Appl Environ Microbiol. 2003 Apr;69(4):2313-20
references: 12676715
references: Science. 1999 May 21;284(5418):1318-22
references: 10334980
references: Appl Environ Microbiol. 1993 Apr;59(4):1181-6
references: 8476292
references: J Mol Endocrinol. 2000 Oct;25(2):169-93
references: 11013345
references: Annu Rev Microbiol. 1995;49:711-45
references: 8561477
references: Nature. 2003 Nov 20;426(6964):306-10
references: 14628055
references: FEMS Microbiol Ecol. 2006 Mar;55(3):479-91
references: 16466387
references: Appl Environ Microbiol. 1999 Sep;65(9):4189-96
references: 10473433
references: FEMS Microbiol Lett. 2004 Jun 15;235(2):357-62
references: 15183885
references: Science. 2013 Mar 15;339(6125):1332-5
references: 23393089
references: Appl Environ Microbiol. 2003 Sep;69(9):5414-22
references: 12957930
references: Environ Toxicol Chem. 2002 Jun;21(6):1184-90
references: 12069301
references: Appl Environ Microbiol. 2001 Jan;67(1):51-8
references: 11133427
references: J Biol Chem. 1958 Oct;233(4):975-81
references: 13587526
references: Appl Environ Microbiol. 1995 Mar;61(3):860-7
references: 7793920
references: Appl Environ Microbiol. 1990 Jan;56(1):298-300
references: 16348104
references: Bull Environ Contam Toxicol. 1983 Oct;31(4):486-93
references: 6640145
references: FEMS Microbiol Ecol. 2000 Apr 1;32(1):35-42
references: 10779617
references: Environ Sci Technol. 2006 Mar 1;40(5):1540-6
references: 16568768
references: J Bacteriol. 2011 Apr;193(8):2078-9
references: 21357488
references: Appl Environ Microbiol. 1994 Nov;60(11):4072-7
references: 16349435
references: J Bacteriol. 2001 Dec;183(24):7094-101
references: 11717267
references: Appl Environ Microbiol. 1987 Feb;53(2):261-5
references: 16347274
references: Appl Environ Microbiol. 2002 Jan;68(1):356-64
references: 11772645
references: Nat Protoc. 2008;3(6):1101-8
references: 18546601
references: Environ Pollut. 1991;71(2-4):131-69
references: 15092118
references: Environ Sci Technol. 2007 Oct 1;41(19):6691-7
references: 17969682
references: BMC Mol Biol. 2008 Jan 22;9:9
references: 18211699
references: Appl Environ Microbiol. 1998 Jun;64(6):1987-90
references: 9603804
references: Appl Environ Microbiol. 1985 Aug;50(2):498-502
references: 16346866
references: Appl Environ Microbiol. 1994 Apr;60(4):1342-6
references: 8017921
references: Appl Environ Microbiol. 2005 May;71(5):2663-76
references: 15870358
references: Appl Environ Microbiol. 2005 Nov;71(11):7531-5
references: 16269796
references: Appl Environ Microbiol. 2000 Jun;66(6):2430-7
references: 10831421
references: Appl Environ Microbiol. 2002 Nov;68(11):5741-5
references: 12406773
references: Appl Environ Microbiol. 2006 Jan;72(1):457-64
references: 16391078
references: FEMS Microbiol Ecol. 2009 Feb;67(2):293-307
references: 19049495
references: Environ Microbiol. 2004 Dec;6(12):1220-7
references: 15560820
references: Methods. 2001 Dec;25(4):402-8
references: 11846609
references: Mol Microbiol. 2003 Apr;48(1):253-67
references: 12657059
references: Proc Natl Acad Sci U S A. 2011 May 24;108(21):8714-9
references: 21555571
references: Science. 1996 Sep 27;273(5283):1795-7
references: 8815541
references: Appl Environ Microbiol. 1999 Nov;65(11):5107-16
references: 10543829
references: Environ Sci Technol. 2011 Sep 15;45(18):7693-700
references: 21875053
references: Nature. 2001 Oct 25;413(6858):860-4
references: 11677611