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

Gonzalez Martinez, Adriana Lizeth

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

Description

Title

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

Author(s)

Gonzalez Martinez, Adriana Lizeth

Issue Date

2025-05-07

Director of Research (if dissertation) or Advisor (if thesis)

Banerjee , Pratik

Committee Member(s)

• Margenot , Andrew J
• Wang, Yi-Cheng

Department of Study

Food Science & Human Nutrition

Discipline

Food Science & Human Nutrition

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

PFAS, soil microbiome, PFOA , PFOS, E. coli O157:H7.

Abstract

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.

Graduation Semester

2025-05

Type of Resource

Thesis

Handle URL

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

Copyright and License Information

Copyright 2025 Adriana Lizeth Gonzalez Martinez

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