Comparative prevalence of the mercury resistance gene merA in human feces, food, and environmental water from Japan, Vietnam, and Ghana
6 affiliations
- 1The United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu, Japan
- 2Center for Medical and Pharmaceutical Research and Service, Thai Binh University of Medicine and Pharmacy, Hung Yen, Vietnam
- 3School of Veterinary Medicine, University of Ghana, Accra, Ghana
- 4Department of Civil and Environmental Engineering, Kindai University, Higashi-Osaka, Japan
- 5Health Administration Center, Gifu University, Gifu, Japan
- 6Institute for Glyco-core Research, Gifu University, Gifu, Japan
Abstract
In this study, we investigated the prevalence and abundance of the mercury resistance gene merA in human feces, retail chicken meat, and environmental water samples collected from Japan, Vietnam, and Ghana. A real-time PCR assay developed in this study demonstrated high specificity toward merA sequences from more than 12 bacterial species. Using this assay, merA was detected in 6.8% of human fecal samples in Japan (n = 29), in contrast to significantly higher rates observed in Vietnam (70.2%, n = 47) and Ghana (97.4%, n = 39). Similar geographic trends were evident in the chicken meat samples: 18.5% in Japan (n = 27), 66% in Vietnam (n = 91), and 90% in Ghana (n = 10). Environmental water samples showed a consistently high merA detection rate across all countries (75–100%, n = 21), with substantially higher gene copy numbers in Vietnam and Ghana than in Japan. merA was detected in some water samples, even when total mercury concentrations were below the detection limit, indicating that molecular detection may offer greater sensitivity than traditional physicochemical methods. Mercury-resistant bacteria were successfully isolated and cultured, and Citrobacter freundii was identified as the representative strain. Genomic analysis revealed that merA was located on an IncFIB plasmid, flanked by insertion sequences, suggesting its potential for horizontal gene transfer. These findings highlight merA as a promising biomarker for environmental mercury exposure and support the utility of fecal merA analysis as a proxy for assessing mercury-related public health risks.
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BibTeX
@article{le2026comparative,
title = {{Comparative prevalence of the mercury resistance gene merA in human feces, food, and environmental water from Japan, Vietnam, and Ghana}},
author = {Yen Hai Le and Judith Dzifa Azumah and Diep Thi Khong and Thang Nam Nguyen and Cornelia Appiah-Kwarteng and Kazuaki Matsui and Mayumi Yamamoto and Kaori Tanaka and Yoshimasa Yamamoto},
journal = {PLOS One},
year = {2026},
month = sep,
doi = {10.1371/journal.pone.0357976},
url = {https://doi.org/10.1371/journal.pone.0357976},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Comparative prevalence of the mercury resistance gene merA in human feces, food, and environmental water from Japan, Vietnam, and Ghana
AU - Yen Hai Le
AU - Judith Dzifa Azumah
AU - Diep Thi Khong
AU - Thang Nam Nguyen
AU - Cornelia Appiah-Kwarteng
AU - Kazuaki Matsui
AU - Mayumi Yamamoto
AU - Kaori Tanaka
AU - Yoshimasa Yamamoto
PY - 2026
DA - 2026/09/08
JO - PLOS One
DO - 10.1371/journal.pone.0357976
UR - https://doi.org/10.1371/journal.pone.0357976
AB - In this study, we investigated the prevalence and abundance of the mercury resistance gene merA in human feces, retail chicken meat, and environmental water samples collected from Japan, Vietnam, and Ghana. A real-time PCR assay developed in this study demonstrated high specificity toward merA sequences from more than 12 bacterial species. Using this assay, merA was detected in 6.8% of human fecal samples in Japan (n = 29), in contrast to significantly higher rates observed in Vietnam (70.2%, n = 47) and Ghana (97.4%, n = 39). Similar geographic trends were evident in the chicken meat samples: 18.5% in Japan (n = 27), 66% in Vietnam (n = 91), and 90% in Ghana (n = 10). Environmental water samples showed a consistently high merA detection rate across all countries (75–100%, n = 21), with substantially higher gene copy numbers in Vietnam and Ghana than in Japan. merA was detected in some water samples, even when total mercury concentrations were below the detection limit, indicating that molecular detection may offer greater sensitivity than traditional physicochemical methods. Mercury-resistant bacteria were successfully isolated and cultured, and Citrobacter freundii was identified as the representative strain. Genomic analysis revealed that merA was located on an IncFIB plasmid, flanked by insertion sequences, suggesting its potential for horizontal gene transfer. These findings highlight merA as a promising biomarker for environmental mercury exposure and support the utility of fecal merA analysis as a proxy for assessing mercury-related public health risks.
SN - 1932-6203
ER -