Synergistic effects of a chalkophore, methanobactin, on microbial methylation of mercury

Xixiang Yin, Lihong Wang, Lijie Zhang, Hongmei Chen, Xujun Liang, Xia Lu, Alan A. DiSpirito, Jeremy D. Semrau, Baohua Gu

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Microbial production of the neurotoxin methylmercury (MeHg) is a significant health and environmental concern, as it can bioaccumulate and biomagnify in the food web. A chalkophore or a copper-binding compound, termed methanobactin (MB), has been shown to form strong complexes with mercury [as Hg(II)] and also enables some methanotrophs to degrade MeHg. It is unknown, however, if Hg(II) binding with MB can also impede Hg(II) methylation by other microbes. Contrary to expectations, MB produced by the methanotroph Methylosinus trichosporium OB3b (OB3b-MB) enhanced the rate and efficiency of Hg(II) methylation more than that observed with thiol compounds (such as cysteine) by the mercury-methylating bacteria Desulfovibrio desulfuricans ND132 and Geobacter sulfurreducens PCA. Compared to no-MB controls, OB3b-MB decreased the rates of Hg(II) sorption and internalization, but increased methylation by 5- to 7-fold, suggesting that Hg(II) complexation with OB3b-MB facilitated exchange and internal transfer of Hg(II) to the HgcAB proteins required for methylation. Conversely, addition of excess amounts of OB3b-MB or a different form of MB from Methylocystis strain SB2 (SB2-MB) inhibited Hg(II) methylation, likely due to greater binding of Hg(II). Collectively, our results underscore the complex roles of microbial exogenous metal-scavenging compounds in controlling net production and bioaccumulation of MeHg in the environment.

Original languageEnglish (US)
Article numbere00122
JournalApplied and Environmental Microbiology
Volume86
Issue number11
DOIs
StatePublished - Jun 1 2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Keywords

  • Anaerobic bacteria
  • Mercury methylation
  • Methanotrophs
  • Methylmercury

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