Issue 1, 2023

Extracellular polymeric substances enhance dissolution and microbial methylation of mercury sulfide minerals

Abstract

Due to the extremely low solubility, mercury sulfide minerals, as the major environmental mercury sinks, are generally considered to be inert mercury species with minimal bioavailability. Here, we demonstrate that extracellular polymeric substances (EPS), continuously secreted and released by anaerobic methylating bacteria, enhance the dissolution processes of cinnabar (α-HgS) minerals. The enhancing effects of EPS occur to a greater extent in the dissolution of nanoparticulate α-HgS compared to the bulk-scale counterpart. The released EPS–Hg(II) species are available for microbial methylation to produce bioaccumulative neurotoxin, methylmercury. This is probably due to the abundant aromatic proteins in EPS that strongly interact with surface Hg(II) via inner-sphere complexation as well as cation–π interaction. Our study discovers the potential environmental risks of “inert” mercury sulfide minerals in natural microbial habitats, particularly benthic biofilms with abundant microbial EPS, transformed to the severely toxic methylmercury. The mechanistic findings will facilitate an accurate understanding of the interactions between soft and transition metals and microorganism-derived organics, which may dictate the environmental fate and impact of these elements.

Graphical abstract: Extracellular polymeric substances enhance dissolution and microbial methylation of mercury sulfide minerals

Supplementary files

Article information

Article type
Paper
Submitted
26 set 2022
Accepted
19 nov 2022
First published
22 nov 2022

Environ. Sci.: Processes Impacts, 2023,25, 44-55

Extracellular polymeric substances enhance dissolution and microbial methylation of mercury sulfide minerals

Z. Zhang, Z. Zhao, Q. Fang, R. Qiao and T. Zhang, Environ. Sci.: Processes Impacts, 2023, 25, 44 DOI: 10.1039/D2EM00394E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements