BIODEGRADATION OF STYRENE BY SOIL INDIGENOUS PSEUDOMONAS SPECIES

This study investigated the Styrene, a ubiquitous industrial monomer, poses environmental and health risks due to its toxicity and persistence in soil and groundwater. In this study, we isolated and characterized indigenous Pseudomonas strains from styrene‑contaminated soils and evaluated their capacity to degrade styrene under laboratory conditions. Soil samples were collected from an olefin‑processing facility site and enriched in mineral salts medium supplemented with styrene vapor as the sole carbon and energy source. Putative Pseudomonas isolates were identified by 16S rRNA gene sequencing and tested for styrene biodegradation in batch cultures. Gas chromatography–mass spectrometry (GC–MS) quantified styrene depletion and intermediate formation over a 7‑day incubation period. Three isolates (designated PSY1, PSY3, and PSY5) achieved >85% depletion of 200 mg L⁻¹ styrene within 96 hours, with half‑lives ranging from 20 to 28 hours. Metabolite profiling revealed accumulation of phenylacetic acid and mandelic acid, implicating the side‐chain oxidation pathway. Optimal degradation occurred at 30 °C, pH 7.0, and with an initial inoculum density of 10⁸ CFU mL⁻¹. PCR screening detected key catabolic genes (styA, styB, paaA) in the fastest‑growing strain, PSY3, suggesting a genetic basis for efficient styrene catabolism. Moreover, PSY3 retained >70% of its biodegradation activity in the presence of 50 mg L⁻¹ heavy metals (Cd²⁺, Pb²⁺), indicating potential for application in multi‑contaminant environments.