Enhanced degradation of dibutyl phthalate using a synthetic mixed bacterial system and its impact on environmental toxicity

Dibutyl phthalate (DBP) is widely used in plastic manufacturing to enhance the flexibility and durability of products. However, DBP is a toxic, persistent environmental pollutant that poses significant risks to ecosystems and human health. This study investigates the DBP degradation efficiency of a mixed bacterial system (MBS) consisting of Serratia sp. G9, Bacillus sp. J7, and Serratia sp. J14, isolated from animal feces and oil-contaminated soil, and evaluates its environmental toxicity for potential practical application. The results show that the MBS exhibited significantly higher DBP removal efficiency and degradation rate compared to a single bacterial system (SBS), achieving near-complete removal of DBP (500 mg/L) within 7 days under optimal conditions. These conditions were determined to be an inoculum dose of 0.8 % (v/v), pH 7, temperature of 35 °C, and shaking speed of 120 rpm. Gas chromatography-mass spectrometry (GC–MS) analysis revealed the breakdown of DBP into non-toxic intermediates, and the degradation pathway was elucidated. Furthermore, aquatic toxicity and neurotoxicity assessments showed a significant reduction in toxicity after treatment, confirming the effectiveness of the MBS in mitigating the environmental impact of DBP pollution. Unlike previous studies that have focused solely on the biological treatability of DBP, this research emphasizes that the MBS offers an effective biological treatment strategy for DBP contamination and provides an environmentally friendly solution by significantly reducing environmental toxicity.