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Integrated Field Lysimetry and Porewater Sampling for Evaluation of Chemical Mobility in Soils and Established Vegetation
Published on: July 4, 2014
Molybdate Causes Target and Nontarget Inhibitory Effects on Microbial Arsenic Methylation in Paddy Soil
Bao-Yun Yang1,2, Chuan Chen1, Shuxin Li3
1Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Environmental Science & Technology
|June 22, 2026
Summary
Molybdate inhibits microbial arsenic methylation in paddy soils, but its effects extend beyond sulfate-reducing bacteria. This impacts our understanding of arsenic cycling and rice disease. Further research is needed to account for these non-target effects.
Area of Science:
- Environmental Microbiology
- Biogeochemistry
- Soil Science
Background:
- Microbial arsenic methylation in flooded paddy soils produces dimethylarsinic acid (DMA), a key factor in rice straighthead disease and yield loss.
- Sulfate-reducing bacteria (SRB) are traditionally considered primary arsenic methylators, often studied using molybdate as a specific inhibitor.
Purpose of the Study:
- To evaluate the specificity of molybdate's inhibition on arsenic methylation by SRB and non-SRB.
- To understand the molecular mechanisms underlying molybdate's effects on arsenic methylation in different bacterial groups.
Main Methods:
- Addition of molybdate to flooded paddy soil and analysis of DMA production and gene expression.
- Metatranscriptomic analysis to assess the impact of molybdate on arsenic methyltransferase (arsM) genes.
- Pure culture experiments with SRB and non-SRB fermentative bacteria, coupled with transcriptomic and metabolomic analyses.
Main Results:
- Molybdate addition significantly suppressed DMA production and the transcription of key arsenic methylation genes in soil.
- Molybdate specifically inhibited SRB growth and arsenic methylation, while partially inhibiting methylation in fermentative bacteria without affecting their growth.
- Molybdate affected the transcription of arsM and thioredoxin (trx) genes and the biosynthesis of S-adenosylmethionine (SAM) in non-SRB.
Conclusions:
- While molybdate effectively inhibits SRB-mediated arsenic methylation, it also exerts non-target effects on arsenic methylation by fermentative bacteria.
- These findings necessitate a re-evaluation of molybdate's utility in solely targeting SRB for arsenic methylation studies.
- Understanding these complex interactions is crucial for accurately assessing microbial contributions to arsenic cycling in paddy soils.
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