ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Microbiological Chemistry and Geomicrobiology
Methanogenesis couples with arsenic methylation in urban interface biofilms under arsenic-phosphorus decoupling stress
Bangxiao Zheng 1,2
Yingsen Lei 1
Yunwei Lin 1
Mingxi Zhou 3
Qing-Fang Bi 4,5,6
1. Xiamen University of Technology, Xiamen, China
2. Helsingin yliopisto, Helsinki, Finland
3. Nanjing Normal University, Nanjing, China
4. Max-Planck-Institut fur Biogeochemie, Jena, Germany
5. Martin-Luther-Universitat Halle-Wittenberg, Halle (Saale), Germany
6. Deutsches Zentrum fur Integrative Biodiversitatsforschung (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
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Abstract
Urban interface biofilms represent understudied microenvironments where atmospheric deposition, microbial colonization, and stormwater runoff intersect, yet their role in contaminant transformation and greenhouse gas dynamics remains poorly understood. Here, we investigated arsenic-phosphorus biogeochemistry and microbial functional gene dynamics across 18 urban interface sites. We discovered a striking arsenic-phosphorus decoupling pattern, with industrial sites exhibiting high arsenic (92.1 mg kg-1) but low phosphorus (322 mg kg-1) concentrations, contrasting with control sites showing the opposite pattern. This decoupling, driven by differential rain-washing dynamics (24.5% As loss vs. 13.5% P loss), created unique selective pressure that drove co-enrichment of arsenic methylation (arsM) and high-affinity phosphate transporter (pstS) genes (r = 0.80, p < 0.001). Methylated arsenic species (MMA + DMA) comprising 18–27% of total arsenic in stormwater runoff provided direct evidence of active arsM-mediated biotransformation. Most significantly, we found strong coupling between arsenic methylation and methanogenic potential, with arsM showing remarkable correlations with mcrA (r = 0.99) and dsrB (r = 0.98). Microcosm incubations confirmed this pattern, revealing CH4 production rates positively correlated with arsM abundance while CO2 flux showed an inverse trend, suggesting arsenic contamination shifts microbial carbon metabolism toward anaerobic pathways. Microbial community analysis revealed selective enrichment of arsenic-tolerant genera (Acinetobacter, Pseudomonas) and reduced alpha diversity at contaminated sites. These findings establish urban interfaces as previously unrecognized hotspots where arsenic transformation and greenhouse gas production are mechanistically coupled, with important implications for understanding urban biogeochemical cycles and their environmental impacts.
Summary
Keywords
Arsenic methylation, Arsenic-phosphorus decoupling, functional genes, methanogenesis, Urban biofilm
Received
28 January 2026
Accepted
18 February 2026
Copyright
© 2026 Zheng, Lei, Lin, Zhou and Bi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Bangxiao Zheng; Qing-Fang Bi
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