| A paracetamol-degrading bacterium F1 was isolated by selective enrichment from activated sludge samples. Based on the morphological characteristics, physiological and biochemical characteristics, 16S rRNA sequence analysis and Biolog identification, this strain was tentatively identified as Cupriavidus necator (previously Ralstonia eutropha). The optimal pH and temperature for F1 biodegradation in shaking flasks were 7.0 and 30℃, respectively. The degrading process of the strain F1 followed the Haldane kinetic model. The maximum specific growth rate and yield coefficient were 0.097 h-1 and 0.21 mg/mg, respectively. At concentrations below 400 mg/mL, the production of CO2was linearly correlated with paracetamol consumed with a coefficient of 1.5805, close to the theoretical coefficient value. Meanwhile, TOC removal efficiency up to 92% was obtained at the initial concentration of 400 mg/L. The results indicated that strain F1 had a high mineralization extent for paracetamol. The identified metabolites suggested a possible main route for paracetamol metabolism, in which acetyl group was replaced by hydrogen atom to form p-aminophenol as the first degradation product. p-aminophenol was further converted to the ring fission substrate p-phenol, which finally participated in TCA cycles. |
