Assessing the efficacy of bioremediation using native microbial consortia for hydrocarbon-contaminated soil in peri-urban regions.

Project Abstract

Bioremediation using native microbial consortia was evaluated to remediate hydrocarbon-contaminated soils in peri-urban regions, addressing the global challenge of emerging contamination hotspots where urban expansion intersects with former industrial sites. The study combines field assessments, laboratory microcosm experiments, and genomic-informed community analyses to determine the efficacy, mechanisms, and sustainability of bioremediation strategies under real-world conditions. We sampled soils from three peri-urban sites with varying histories of hydrocarbon exposure (petroleum leaks, spills, and accidental releases) and characterized them for hydrocarbon fractions (aliphatic and aromatic hydrocarbons), total petroleum hydrocarbons (TPH), moisture, pH, texture, organic matter, and indigenous microbial diversity using 16S rRNA gene amplicon sequencing. A defined native microbial consortium, enriched from uncontaminated and contaminated site soils, was introduced at multiple doses to simulate biostimulation and bioaugmentation scenarios. Over a 12-week period, we monitored hydrocarbon concentration reductions (TPH, BTEX components, and n-alkane series), enzyme activities (dehydrogenase, peroxidase, and oxygenases), and complementary indicators of soil health (aggregate stability, nutrient flux, and respiration rates). Metagenomic and metatranscriptomic analyses elucidated functional gene dynamics associated with hydrocarbon degradation pathways (alkB, C23O, xyl operons, nah-like genes) and stress responses, revealing shifts in microbial networks and potential key degraders. Statistical analyses, including mixed-effects models and multivariate redundancy analysis, assessed the influence of environmental variables (moisture, nutrient amendments, oxygen availability) on degradation rates and microbial function, while network analysis identified keystone taxa and synergistic interactions within the consortia and native communities. Results demonstrated site-specific degradation efficiency ranging from 45% to 82% TPH reduction within 12 weeks, with higher performance associated with optimal moisture and moderate nutrient supplementation that promoted expression of alkane and aromatic degradation pathways. Indigenous taxa from genera such as Pseudomonas, Sphingomonas, Rhodococcus, and Mycobacterium were enriched, and the introduced consortia significantly enhanced pathway gene abundance and transcript levels, suggesting a robust synergistic effect between native ecosystems and applied consortia. Functional redundancy and resilience were observed, with degraded fraction profiles indicating parallel biodegradation routes for aliphatics and aromatics. Soil health indicators improved in treated plots, evidenced by increased enzymatic activity and improved aggregate stability, while monitoring for potential trade-offs highlighted the necessity of maintaining native microbial diversity to sustain long-term remediation. The study provides actionable guidance on selecting and applying native microbial consortia for peri-urban remediation, highlighting optimal dosing, carbon/nitrogen balance, moisture regimes, and anticipated timelines under variable climatic and soil conditions. The findings contribute to a framework for evaluating bioremediation performance that integrates chemical degradation metrics with functional and community-level insights, enabling scalable, context-specific strategies for sustainable management of hydrocarbon-contaminated soils in peri-urban landscapes.

Project Overview

What This Project Is About

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The project looks at using natural soil microbes that work together (a microbial consortium) to clean up soils damaged by oil and other hydrocarbons in peri-urban areas. It tests whether these native microbes can break down pollutants effectively and safely, without needing harsh chemicals.

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The Problem It Addresses

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Objectives of the Project

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1. Identify native microbial communities present in polluted peri-urban soils.
2. Evaluate how well these microbes break down hydrocarbon pollutants in lab and field settings.
3. Compare single strains versus consortia to see which works better for cleanup.
4. Monitor changes in soil health markers during bioremediation.
5. Assess potential by-products and ensure there are no new risks.

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What You Will Do Step by Step

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Collect soil samples from polluted sites and characterize their hydrocarbon content. Isolate native microbes and form simple consortia. Test degradation rates in controlled lab setups, then pilot in small field plots. Measure pollutant levels, soil microbes, and key soil health indicators over time. Analyze data to compare effectiveness and draw practical recommendations.

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Expected Outcome