Toxicity Screening of Wildfire-Impacted Residential Soils Using a Multi-Stress Escherichia coli Bioluminescent Bioreporter Panel

Wildfires that destroy residential infrastructure can generate chemically complex soil contamination; however, post-fire screening is often limited and does not directly reflect biological hazards. Herein, we integrated a multi-stress lux-based whole-cell bioreporter panel of genetically engineered Escherichia coli strains with non-targeted LC-MS profiling to obtain a mechanism-informed assessment of soils collected from a residential property impacted by the January 2025 Los Angeles wildfires. The bioreporter panel resolved heterogeneous and statistically significant stress signatures across the analyzed samples. In particular, extracts from U3–U5 produced selective suppression of the membrane and fatty acid biosynthesis bioreporters, along with reduced growth. In contrast, extract U5 induced a proteotoxic heat-shock response signature. In parallel, non-targeted LC-MS detected 1813 chemical features and enabled the putative annotation of a subset of signals consistent with combustion-derived organics and reactive electrophiles, providing a chemical context for the observed bioassay fingerprints. The integrated workflow provides mechanism-resolved hazard triage within 48 h, as implemented herein (24 h elutriate preparation plus up to 20 h microplate kinetics), supporting the prioritization of hotspots for confirmatory analysis, remediation, and risk assessment.