Biotic and Abiotic Degradation of Methylmercury in Aquatic Ecosystems: A Review

  • Hongxia Du
  • Ming Ma
  • Yasuo IgarashiEmail author
  • Dingyong WangEmail author
Focused Review


Mercury (Hg) methylation and demethylation is supposed to simultaneously exist in the environment and form a cycle, which determines the net production of methylmercury (MeHg). Exploring the mechanisms of MeHg formation and degradation, and its final fate in the natural environment is essential to understanding the biogeochemical cycle of Hg. However, MeHg demethylation has been less studied in the past years comparing with Hg methylation, particularly in anaerobic microorganisms whose demethylation role has been under-evaluated. This review described the current state of knowledge on biotic (microorganisms) and abiotic demethylation (photodegradation, chemical degradation) of MeHg. The decomposition of MeHg performed by microorganisms has been identified as two different pathways, reductive demethylation (RD) and oxidative demethylation (OD). Anaerobic and aerobic microorganisms involved in the process of RD and OD, influencing factors as well as research background and histories are systematically described in this review. It is predicted that the photodegradation mechanism, as well as anaerobic microorganisms involved in MeHg formation and degradation cycle will be the focus of future research.


Methylmercury Biotic demethylation Abiotic demethylation Mechanisms 



This work was supported by the National Natural Science Foundation of China (41603098 & 41573105), and the Natural Science Foundation of Chongqing (cstc2017jcyjAX0250).

Supplementary material

128_2018_2530_MOESM1_ESM.docx (40 kb)
Supplementary material 1 (DOCX 40 KB)


  1. Abelson PH (1970) Methyl mercury. Science 169:237–237. CrossRefGoogle Scholar
  2. Asaduzzaman AM, Schreckenbach G (2011) Degradation mechanism of methyl mercury selenoamino acid complexes: a computational study. Inorg Chem 50:2366–2372. CrossRefGoogle Scholar
  3. Barkay T, Wagnerdöbler I (2005) Microbial transformations of mercury: potentials, challenges, and achievements in controlling mercury toxicity in the environment. Adv Appl Microbiol 57:1–52. CrossRefGoogle Scholar
  4. Barkay T, Miller SM, Summers AO (2003) Bacterial mercury resistance from atoms to ecosystems. Fems Microbiol Rev 27:355–384. CrossRefGoogle Scholar
  5. Bhuiyan MAH, Islam MA, Dampare SB, Parvez L, Suzuki S (2010) Evaluation of hazardous metal pollution in irrigation and drinking water systems in the vicinity of a coal mine area of northwestern Bangladesh. J Hazard Mater 179:1065–1077. CrossRefGoogle Scholar
  6. Black FJ, Poulin BA, Flegal AR (2012) Factors controlling the abiotic photo-degradation of monomethylmercury in surface waters. Geochim Cosmochim Acta 84:492–507. CrossRefGoogle Scholar
  7. Boyd ES, King S, Tomberlin JK et al (2010) Methylmercury enters an aquatic food web through acidophilic microbial mats in Yellowstone National Park, Wyoming. Environ Microbiol 11:950–959. CrossRefGoogle Scholar
  8. Bridou R, Monperrus M, Gonzalez PR et al (2011) Simultaneous determination of mercury methylation and demethylation capacities of various sulfate-reducing bacteria using species-specific isotopic tracers. Environ Toxicol Chem 30:337–344. CrossRefGoogle Scholar
  9. Brown NL, Misra TK, Winnie JN, Schmidt A, Seiff M, Silver S (1986) The nucleotide sequence of the mercuric resistance operons of plasmid R100 and transposon Tn501: further evidence for mer genes which enhance the activity of the mercuric ion detoxification system. Mol Gen Genet 202:143–151. CrossRefGoogle Scholar
  10. Bystrom E (2008) Assessment of mercury methylation and demethylation with focus on chemical speciation and biological processes. Dissertation, Georgia Institute of TechnologyGoogle Scholar
  11. Celo V, Lean DRS, Scott SL (2006) Abiotic methylation of mercury in the aquatic environment. Sci Total Environ 368:126–137. CrossRefGoogle Scholar
  12. Chen J, Pehkonen SO, Lin CJ (2003) Degradation of monomethylmercury chloride by hydroxyl radicals in simulated natural waters. Water Res 37:2496–2504. CrossRefGoogle Scholar
  13. Clarkson TW, Magos L (2006) The toxicology of mercury and its chemical compounds. Crit Rev Toxicol 36:609–662. CrossRefGoogle Scholar
  14. Compeau GC, Bartha R (1985) Sulfate-reducing bacteria: principal methylators of mercury in anoxic estuarine sediment. Appl Environ Microbiol 50:498–502Google Scholar
  15. Craig PJ, George E, Jenkins RO (2003) Occurrence and pathways of organometallic compounds in the environment-general considerations. Wiley, New York, pp 1–55. CrossRefGoogle Scholar
  16. Eckley CS, Hintelmann H (2006) Determination of mercury methylation potentials in the water column of lakes across Canada. Sci Total Environ 368:111–125. CrossRefGoogle Scholar
  17. Fernándezgómez C, Drott A, Björn E et al (2013) Towards universal wavelength-specific photodegradation rate constants for methyl mercury in humic waters, exemplified by a boreal lake-wetland gradient. Environ Sci Technol 47:6279–6287. CrossRefGoogle Scholar
  18. Gilmour CC, Podar M, Bullock AL et al (2013) Mercury methylation by novel microorganisms from new environments. Environ Sci Technol 47:11810–11820. CrossRefGoogle Scholar
  19. Gilmour CC, Bullock AL, Mcburney A, Podar M, Elias DA (2018) Robust mercury methylation across diverse methanogenic archaea. Mbio 9:e02403–e02417. CrossRefGoogle Scholar
  20. Hammerschmidt CR, Fitzgerald WF (2008) Methylmercury in arctic Alaskan mosquitoes: implications for impact of atmospheric mercury depletion events. Environ Chem 5:127–130. CrossRefGoogle Scholar
  21. Hammerschmidt CR, Fitzgerald WF (2010) Iron-mediated photochemical decomposition of methylmercury in an arctic Alaskan lake. Environ Sci Technol 44:6138–6143. CrossRefGoogle Scholar
  22. Han S, Obraztsova A, Pretto P et al (2007) Biogeochemical factors affecting mercury methylation in sediments of the Venice Lagoon, Italy. Environ Toxicol Chem 26:655–663CrossRefGoogle Scholar
  23. Hines ME, Faganeli J, Adatto I, Horvat M (2006) Microbial mercury transformations in marine, estuarine and freshwater sediment downstream of the Idrija Mercury Mine, Slovenia. Appl Geochem 21:1924–1939. CrossRefGoogle Scholar
  24. Hines ME, Poitras EN, Covelli S et al (2012) Mercury methylation and demethylation in Hg-contaminated lagoon sediments (Marano and Grado Lagoon, Italy). Estuar Coast Shelf Sci 113:85–95. CrossRefGoogle Scholar
  25. Hsu-Kim H, Kucharzyk KH, Zhang T, Deshusses MA (2013) Mechanisms regulating mercury bioavailability for methylating microorganisms in the aquatic environment: a critical review. Environ Sci Technol 47:2441–2456. CrossRefGoogle Scholar
  26. Hu H, Lin H, Zheng W et al (2013) Oxidation and methylation of dissolved elemental mercury by anaerobic bacteria. Nat Geosci 6:751–754. CrossRefGoogle Scholar
  27. Inoue C, Sugawara K, Kusano T (1991) The merR regulatory gene in Thiobacillus ferrooxidans. is spaced apart from the mer structural genes. Mol Microbiol 5:2707–2718. CrossRefGoogle Scholar
  28. Khan MAK, Wang F (2010) Chemical demethylation of methylmercury by selenoamino acids. Chem Res Toxicol 23:1202–1206. CrossRefGoogle Scholar
  29. Kholodii GY, Yurieva OV, Lomovskaya OL et al (1993) Tn5053, a mercury resistance transposon with integron’s ends. J Mol Biol 230:1103–1107. CrossRefGoogle Scholar
  30. Kim EH, Mason RP, Porter ET, Soulen HL (2006) The impact of resuspension on sediment mercury dynamics, and methylmercury production and fate: a mesocosm study. Mar Chem 102:300–315. CrossRefGoogle Scholar
  31. Klapstein SJ, O’Driscoll NJ (2018) Methylmercury biogeochemistry in freshwater ecosystems: a review focusing on DOM and photodemethylation. Bull Environ Contam Toxicol 100:14–25. CrossRefGoogle Scholar
  32. Landner L (1971) Biochemical model for the biological methylation of mercury suggested from methylation studies in vivo with Neurospora crassa. Nature 230:452–454. CrossRefGoogle Scholar
  33. Lawson NM, Mason RP, Laporte JM (2001) The fate and transport of mercury, methylmercury, and other trace metals in Chesapeake Bay tributaries. Water Res 35:501–515. CrossRefGoogle Scholar
  34. Lehnherr I, St Louis V (2009) Importance of ultraviolet radiation in the photodemethylation of methylmercury in freshwater ecosystems. Environ Sci Technol 43:5692–5698. CrossRefGoogle Scholar
  35. Li Y, Cai Y (2013) Progress in the study of mercury methylation and demethylation in aquatic environments. Sci Bull 58:177–185. CrossRefGoogle Scholar
  36. Li Y, Mao Y, Liu G et al (2010) Degradation of methylmercury and its effects on mercury distribution and cycling in the Florida Everglades. Environ Sci Technol 44:6661–6666. CrossRefGoogle Scholar
  37. Liebert CA, Wireman J, Smith T, Summers AO (1997) Phylogeny of mercury resistance (mer) operons of gram-negative bacteria isolated from the fecal flora of primates. Appl Environ Microbiol 63:1066–1076Google Scholar
  38. Lu X, Liu Y, Johs A et al (2016) Anaerobic mercury methylation and demethylation by Geobacter Bemidjiensis Bem. Environ Sci Technol 50:4366–4373. CrossRefGoogle Scholar
  39. Marvindipasquale M, Oremland RS (1998) Bacterial methylmercury degradation in Florida everglades peat sediment. Environ Sci Technol 32:2556–2563. CrossRefGoogle Scholar
  40. Marvindipasquale M, Agee J, Mcgowan C et al (2000) Methyl-mercury degradation pathways: a comparison among three mercury-impacted ecosystems. Environ Sci Technol 34:4908–4916. CrossRefGoogle Scholar
  41. Mason RP, Benoit JM (2003) Organomercury compounds in the environment. In: Organometallic compounds in the environment. Wiley, New York, pp 57–99. CrossRefGoogle Scholar
  42. Monperrus M, Tessier E, Amouroux D, Leynaert A, Huonnic P, Donard OFX (2007) Mercury methylation, demethylation and reduction rates in coastal and marine surface waters of the Mediterranean Sea. Mar Chem 107:49–63. CrossRefGoogle Scholar
  43. Moore B (1960) A new screen test and selective medium for the rapid detection of epidemic strains of Staph. aureus. Lancet 276:453–458. CrossRefGoogle Scholar
  44. Oremland RS, Culbertson CW, Winfrey MR (1991) Methylmercury decomposition in sediments and bacterial cultures: involvement of methanogens and sulfate reducers in oxidative demethylation. Appl Environ Microbiol 57:130–137Google Scholar
  45. Oremland RS, Miller LG, Dowdle P, Connell T, Barkay T (1995) Methylmercury oxidative degradation potentials in contaminated and pristine sediments of the carson river, Nevada. Appl Environ Microbiol 61:2745–2753Google Scholar
  46. Pak KR, Bartha R (1998) Mercury methylation and demethylation in anoxic lake sediments and by strictly anaerobic bacteria. Appl Environ Microbiol 64:1013–1017Google Scholar
  47. Parks JM, Johs A, Podar M et al (2013) The genetic basis for bacterial mercury methylation. Science 339:1332–1335. CrossRefGoogle Scholar
  48. Podar M, Gilmour CC, Brandt CC et al (2015) Global prevalence and distribution of genes and microorganisms involved in mercury methylation. Sci Adv 1:e1500675. CrossRefGoogle Scholar
  49. Poissant L, Zhang HH, Canário J, Constant P (2008) Critical review of mercury fates and contamination in the Arctic tundra ecosystem. Sci Total Environ 400:173–211. CrossRefGoogle Scholar
  50. Qian Y, Yin X, Lin H et al (2014) Why dissolved organic matter (DOM) enhances photodegradation of methylmercury. Environ Sci Technol Lett 1:426–431. CrossRefGoogle Scholar
  51. Ramial PS, Rudd JWM, Furutam A, Xun L (1985) The effect of pH on methyl mercury production and decomposition in lake sediments. Can J Fish Aquat Sci 42:685–692CrossRefGoogle Scholar
  52. Raposo JC, Gihring TM, Dalton DD et al (2008) Mercury biomethylation assessment in the estuary of Bilbao (North of Spain). Environ Pollut 156:482–488. CrossRefGoogle Scholar
  53. Richmond MH, Madeleine J (1964) Co-transduction by a staphylococcal phage of the genes responsible for penicillinase synthesis and resistance to mercury salts. Nature 202:1360–1361. CrossRefGoogle Scholar
  54. Robinson JB, Tuovinen OH (1984) Mechanisms of microbial resistance and detoxification of mercury and organomercury compounds: physiological, biochemical, and genetic analyses. Microbiol Rev 48:95–124Google Scholar
  55. Schaefer JK, Letowski J, Barkay T (2002) Mer-mediated resistance and volatilization of Hg(II) under anaerobic conditions. Geomicrobiol J 19:87–102. CrossRefGoogle Scholar
  56. Sellers P, Kelly CA, Rudd JWM, Machutchon AR (1996) Photodegradation of methylmercury in lakes. Nature 380:694–697. CrossRefGoogle Scholar
  57. Spangler WJ, Spigarelli JL, Rose JM, Flippin RS, Miller HH (1973) Degradation of methylmercury by bacteria isolated from environmental samples. Appl Microbiol 25:488–493Google Scholar
  58. Suda I, Suda M, Hirayama K (1993) Degradation of methyl and ethyl mercury by singlet oxygen generated from sea water exposed to sunlight or ultraviolet light. Arch Toxicol 67:365–368. CrossRefGoogle Scholar
  59. Susana S, Dias T, Ramalhosa E (2011) Mercury methylation versus demethylation: main processes involved. In: AP C (ed) Methylmercury: formation, sources and health effects. Nova Science Publishers, New York, pp 1–24Google Scholar
  60. Tai C, Li Y, Yin Y, Scinto LJ, Jiang G, Cai Y (2014) Methylmercury photodegradation in surface water of the Florida Everglades: importance of dissolved organic matter-methylmercury complexation. Environ Sci Technol 48:7333–7340. CrossRefGoogle Scholar
  61. Tonomura K, Kanzaki F (1969) The reductive decomposition of organic mercurials by cell-free extract of a mercury-resistant pseudomonad. BBA-Mol Cell Res 184:227–229. CrossRefGoogle Scholar
  62. Tossell JA (1998) Theoretical study of the photodecomposition of methyl Hg complexes. J Phys Chem A 102:3587–3591. CrossRefGoogle Scholar
  63. Weber JH (1993) Review of possible paths for abiotic methylation of mercury(II) in the aquatic environment. Chemosphere 26:2063–2077. CrossRefGoogle Scholar
  64. Yu R, Reinfelder JR, Hines ME, Barkay T (2013) Mercury methylation by the methanogen methanospirillum hungatei. Appl Environ Microbiol 79:6325–6330. CrossRefGoogle Scholar
  65. Zhang T, Hsu-Kim H (2010) Photolytic degradation of methylmercury enhanced by binding to natural organic ligands. Nat Geosci 3:473–476. CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.College of Resources and EnvironmentSouthwest UniversityChongqingChina
  2. 2.Chongqing Key Laboratory of Bio-Resource for BioenergySouthwest UniversityChongqingChina

Personalised recommendations