Impact of soil contamination by PFAS on pathogenic Escherichia coli O157:H7 physiology and the soil microbiome

Per- and polyfluoroalkyl substances (PFAS), a class of persistent synthetic chemicals, have been widely used since the 1940s in industrial and consumer products. Their environmental stability and resistance to degradation have led to widespread contamination of water, air, soil, and food systems. Recent studies have highlighted PFAS contamination in agricultural soils, raising concerns about their impact on soil ecosystems and food safety. The effects of PFAS on soil microbial communities and pathogen dynamics remain poorly understood. This study investigates the impact of two common PFAS compounds, perfluorooctanoic acid (PFOA) and perfluoro octane sulfonate (PFOS) at environmental relevant concentrations, on the soil microbiome and the survival of Escherichia coli O157:H7, a major foodborne pathogen. Using soil microcosm experiments, this research examines how PFAS exposure affects E. coli persistence, microbial gene expression, and overall soil microbial composition. Results revealed that E. coli exhibited long-term survival in PFAS-contaminated soils, with PFOS exerting a slightly greater suppressive effect than PFOA, though differences were not statistically significant. Gene expression analysis showed significant upregulation of stress- and virulence-related genes, indicating persistent chemical stress and the potential enhancement of pathogenic traits. Initially, marked upregulation of chpB, oxyR, bolA, and eaeA was observed under PFOS exposure, whereas fliC was significantly downregulated under PFOA exposure. After two weeks, stress-response genes, such as rpoH and rpoS, exhibited substantial downregulation, indicating gradual adaptation, although oxyR and bolA remained elevated under PFOA exposure. By the end of four weeks, genes including stx1a, eaeA, chpB, and oxyR showed elevated expression, indicating a later-stage stress adaptation mechanism. PFAS exposure significantly reduced phosphomonoesterase (PME) and β-glucosidase activities, implicating disruptions in microbial phosphorus and carbon cycling. Soil C mineralization rates assessed as CO₂ production, showed an initial decline followed by stabilization, specially under PFOA (25 ng/g) during the first week. High-throughput sequencing revealed compound-specific shifts in microbial community composition, including suppression of Pseudomonas and enrichment of resilient genera such as Bacillus, Geobacter, and Anaeromyxobacter. These findings reveal the ecological risks of PFAS in agricultural environments reinforcing the urgency for targeted mitigation and policy interventions to preserve both soil health and food system integrity.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Food Science & Human Nutrition

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Gonzalez Martinez, Adriana Lizeth

Contributors dc:contributor

• Banerjee ,. Pratik
• Margenot ,. Andrew J
• Wang, Yi-Cheng

• Pfas
• Soil Microbiome
• Pfoa
• Pfos
• E. Coli O157:h7.

Statement dc:rights

• Copyright 2025 Adriana Lizeth Gonzalez Martinez

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129746

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129746