Light-independent phytoplankton degradation and detoxification of methylmercury in water

Xujun Liang; Huan Zhong; Alexander Johs; Pei Lei; Jin Zhang; Neslihan Taş; Lijie Zhang; Linduo Zhao; Nali Zhu; Xixiang Yin; Lihong Wang; Eddy Y. Zeng; Yuxi Gao; Jiating Zhao; Dale A. Pelletier; Eric M. Pierce; Baohua Gu

doi:10.1038/s44221-023-00117-1

Light-independent phytoplankton degradation and detoxification of methylmercury in water

Xujun Liang
, Huan Zhong
, Alexander Johs
, Pei Lei
, Jin Zhang
, Neslihan Taş
, Lijie Zhang
, Linduo Zhao
, Nali Zhu
, Xixiang Yin
, Lihong Wang
, Eddy Y. Zeng
, Yuxi Gao
, Jiating Zhao
, Dale A. Pelletier
, Eric M. Pierce
, Baohua Gu

Research output: Contribution to journal › Article › peer-review

22 Scopus citations

Abstract

Phytoplankton serves as a key entry point for the trophic transfer and bioaccumulation of the neurotoxin methylmercury (MeHg) in aquatic food webs. However, it is unclear whether and how phytoplankton itself may degrade and metabolize MeHg in the dark. Here, using several strains of the freshwater alga Chlorella vulgaris, the marine diatom Chaetoceros gracilis and two cyanobacteria (or blue-green algae), we report a light-independent pathway of MeHg degradation in water by phytoplankton, rather than its associated bacteria. About 36–85% of MeHg could be degraded intracellularly to inorganic Hg(II) and/or Hg(0) via dark reactions. Endogenic reactive oxygen species, particularly singlet oxygen, were identified as the main driver of MeHg demethylation. Given the increasing incidence of algal blooms in lakes and marine systems globally, these findings underscore the potential roles of phytoplankton demethylation and detoxification of MeHg in aquatic ecosystems and call for improved modelling and assessment of MeHg bioaccumulation and environmental risks.

Original language	English
Pages (from-to)	705-715
Number of pages	11
Journal	Nature Water
Volume	1
Issue number	8
DOIs	https://doi.org/10.1038/s44221-023-00117-1
State	Published - Aug 2023

Funding

We thank X. Yin and Z. Li for technical assistance in experiments and biochemical analyses. This research was supported in part by the Office of Biological and Environmental Research within the Office of Science of the US Department of Energy (DOE), as part of the Critical Interfaces Science Focus Area project at Oak Ridge National Laboratory (ORNL), and by the National Natural Science Foundation of China (12222509 and 42107383) and the Natural Science Foundation of Jiangsu Province (BK20200322). The DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). ORNL is managed by UT-Battelle, LLC under contract no. DE-AC05-00OR22725 with DOE.

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10.1038/s44221-023-00117-1

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title = "Light-independent phytoplankton degradation and detoxification of methylmercury in water",

abstract = "Phytoplankton serves as a key entry point for the trophic transfer and bioaccumulation of the neurotoxin methylmercury (MeHg) in aquatic food webs. However, it is unclear whether and how phytoplankton itself may degrade and metabolize MeHg in the dark. Here, using several strains of the freshwater alga Chlorella vulgaris, the marine diatom Chaetoceros gracilis and two cyanobacteria (or blue-green algae), we report a light-independent pathway of MeHg degradation in water by phytoplankton, rather than its associated bacteria. About 36–85\% of MeHg could be degraded intracellularly to inorganic Hg(II) and/or Hg(0) via dark reactions. Endogenic reactive oxygen species, particularly singlet oxygen, were identified as the main driver of MeHg demethylation. Given the increasing incidence of algal blooms in lakes and marine systems globally, these findings underscore the potential roles of phytoplankton demethylation and detoxification of MeHg in aquatic ecosystems and call for improved modelling and assessment of MeHg bioaccumulation and environmental risks.",

author = "Xujun Liang and Huan Zhong and Alexander Johs and Pei Lei and Jin Zhang and Neslihan Ta{\c s} and Lijie Zhang and Linduo Zhao and Nali Zhu and Xixiang Yin and Lihong Wang and Zeng, \{Eddy Y.\} and Yuxi Gao and Jiating Zhao and Pelletier, \{Dale A.\} and Pierce, \{Eric M.\} and Baohua Gu",

note = "Publisher Copyright: {\textcopyright} The Author(s), under exclusive licence to Springer Nature Limited 2023.",

year = "2023",

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doi = "10.1038/s44221-023-00117-1",

language = "English",

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T1 - Light-independent phytoplankton degradation and detoxification of methylmercury in water

AU - Liang, Xujun

AU - Zhong, Huan

AU - Johs, Alexander

AU - Lei, Pei

AU - Zhang, Jin

AU - Taş, Neslihan

AU - Zhang, Lijie

AU - Zhao, Linduo

AU - Zhu, Nali

AU - Yin, Xixiang

AU - Wang, Lihong

AU - Zeng, Eddy Y.

AU - Gao, Yuxi

AU - Zhao, Jiating

AU - Pelletier, Dale A.

AU - Pierce, Eric M.

AU - Gu, Baohua

PY - 2023/8

Y1 - 2023/8

N2 - Phytoplankton serves as a key entry point for the trophic transfer and bioaccumulation of the neurotoxin methylmercury (MeHg) in aquatic food webs. However, it is unclear whether and how phytoplankton itself may degrade and metabolize MeHg in the dark. Here, using several strains of the freshwater alga Chlorella vulgaris, the marine diatom Chaetoceros gracilis and two cyanobacteria (or blue-green algae), we report a light-independent pathway of MeHg degradation in water by phytoplankton, rather than its associated bacteria. About 36–85% of MeHg could be degraded intracellularly to inorganic Hg(II) and/or Hg(0) via dark reactions. Endogenic reactive oxygen species, particularly singlet oxygen, were identified as the main driver of MeHg demethylation. Given the increasing incidence of algal blooms in lakes and marine systems globally, these findings underscore the potential roles of phytoplankton demethylation and detoxification of MeHg in aquatic ecosystems and call for improved modelling and assessment of MeHg bioaccumulation and environmental risks.

AB - Phytoplankton serves as a key entry point for the trophic transfer and bioaccumulation of the neurotoxin methylmercury (MeHg) in aquatic food webs. However, it is unclear whether and how phytoplankton itself may degrade and metabolize MeHg in the dark. Here, using several strains of the freshwater alga Chlorella vulgaris, the marine diatom Chaetoceros gracilis and two cyanobacteria (or blue-green algae), we report a light-independent pathway of MeHg degradation in water by phytoplankton, rather than its associated bacteria. About 36–85% of MeHg could be degraded intracellularly to inorganic Hg(II) and/or Hg(0) via dark reactions. Endogenic reactive oxygen species, particularly singlet oxygen, were identified as the main driver of MeHg demethylation. Given the increasing incidence of algal blooms in lakes and marine systems globally, these findings underscore the potential roles of phytoplankton demethylation and detoxification of MeHg in aquatic ecosystems and call for improved modelling and assessment of MeHg bioaccumulation and environmental risks.

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VL - 1

SP - 705

EP - 715

JO - Nature Water

JF - Nature Water

IS - 8

ER -

Light-independent phytoplankton degradation and detoxification of methylmercury in water

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