The metabolic pathway of THF-degrading composite bacteria and its immobilized microspheres

Abstract

Tetrahydrofuran (THF), as a typical recalcitrant organic pollutant, poses a serious threat to ecological security and human health due to its environmental persistence. This study aimed to systematically elucidate the metabolic pathway of THF degradation by efficient composite bacteria and develop immobilized enhancement technology to improve their degradation performance. First, the key metabolic pathway for THF degradation by the composite bacteria was analyzed using GC–MS. Second, sodium alginate-chitosan microspheres encapsulating the composite bacteria were prepared, and the preparation process parameters were systematically optimized through single-factor experiments and Box-Behnken response surface methodology. Metabolic pathway analysis revealed that THF undergoes hydroxylation-induced ring-opening catalyzed by monooxygenase, yielding 4-hydroxybutanal, which is subsequently oxidized to 4-hydroxybutyric acid, and ultimately mineralized to CO₂ and H₂O. Under varying THF initial concentrations (180–540 mg/L) and temperatures (25–40 °C), the immobilized composite bacteria demonstrated significantly higher degradation capability and environmental adaptability compared to free bacteria, with markedly improved degradation efficiency. Furthermore, the immobilized microspheres exhibited excellent reusability, maintaining efficient THF removal rates after 5 consecutive cycles. This research elucidated the metabolic mechanism of THF degradation by the composite bacteria and developed a highly efficient and stable preparation process for the immobilized bacterial agent.