Bioremediation of soil contaminated with cassava mill effluents - A structural, functional, and metagenomics approach
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Date
2025
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Abstract
Cassava mill effluent (CME) is a toxic pollutant that acidifies soil, accumulates cyanide and heavy metals, and drastically reduces soil fertility and microbial diversity. To address this, we evaluated the bioremediation po- tential of selected cyanide-degrading bacteria ( Pseudomonas fluorescens, Bacillus pumilus, Pseudomonas putida , and Pseudomonas stutzeri ) in CME-polluted soil using an integrated approach combining enzymatic assays, metage- nomic profiling, and molecular docking analyses. In laboratory microcosms, these strains significantly improved soil conditions over 20 days: soil pH increased from ∼4.8 to ∼7.4, cyanide levels fell by over 80 %, and key heavy metals (e.g., Cu2 + , Cd2 + ) were eliminated or sharply reduced. Heterotrophic bacterial counts rebounded, and enzymatic activity (nitrilase, cyanide dihydratase) correlated with the degradation of cyanide. Metagenomic sequencing revealed a restored and more diverse microbial community dominated by beneficial genera such as Pseudomonas and Bacillus after treatment. Molecular docking simulations confirmed cyanide binding to the bacterial enzymes, supporting the degradation mechanism. Our findings demonstrate that a targeted microbial consortium can detoxify CME-contaminated soils and restore soil health. This integrative structural–functional strategy provides a promising framework for sustainable remediation of cassava processing waste in agricultural lands.