Bioremediation of Soil Contaminants Using Lactic Acid Bacteria: A Fermentation-Based Approach for Sustainable Environmental Cleanup

Introduction:
Soil contamination remains a critical environmental challenge in the world including Pakistan, where traditional remediation methods are often economically and ecologically unsustainable. This study investigates Lactic Acid Bacteria (LAB) as a bioremediation agent, leveraging Pakistan’s agro-industrial byproducts (molasses-based media) for cost-effective fermentation.

Methodology: We isolated LAB from local soil samples and assessed their capacity to degrade contaminants such as lead, cadmium, and benzene. The strains were cultured in a 15 L Stirred Tank Bioreactor using MRS broth (pH 6.2) supplemented with 10% sugarcane molasses as a low-cost carbon source. Fermentation was performed under controlled conditions (37 °C, 150 rpm, 1.0 vvm aeration, 72 h). The fermented broth was applied to contaminated soil at 10% (v/w), with nutrient modulation achieved through the addition of 5% compost. Pollutant degradation was analyzed using atomic absorption spectrophotometry (AAS) for heavy metals and gas chromatography (GC) for benzene, while nutrient availability was assessed through soil profiling.

Results: LAB reduced heavy metals and organic pollutants by up to 45% within 14 days, with the highest degradation observed for cadmium and benzene, alongside improved soil N, P, and K levels.

Conclusion: LAB fermentation offers a scalable and sustainable approach for soil bioremediation.