Efficient Biodegradation of Cefixime by the Newly Isolated Strain Pseudochrobactrum asaccharolyticum TY12 and Insights into Its Degradation Mechanism

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Abstract
Cephalosporin residues in agricultural soils, food systems, and aquatic environments pose severe threats to food safety, public health, and the ecological environment. While biodegradation represents a promising remediation strategy, the degradation mechanisms for most cephalosporins remain elusive. In this study, Pseudochrobactrum asaccharolyticum TY12 was isolated and demonstrated a broad-spectrum ability to degrade multiple cephalosporins. Notably, strain TY12 exhibited the highest cefixime (CFX) degradation efficiency, achieving a 93.87% removal of 100 mg/L CFX within 12 h. Ten degradation products of CFX were identified via high-resolution mass spectrometry, leading to a proposed degradation pathway. Notably, these products exhibited significantly attenuated antibacterial activity. Transcriptomic analysis and heterologous expression identified β-lactamase TY3865 as the key enzyme. Furthermore, molecular docking and site-directed mutagenesis revealed the residues critical for its catalytic activity. These findings provide mechanistic insights into antibiotic biodegradation and demonstrate the potential of TY12 for treating cephalosporin-contaminated wastewater.
Funding Information
  • Natural Science Foundation of Hebei Province (B2024201049)
  • Natural Science Foundation of Hebei Province (C2022201042)
  • Natural Science Foundation of Hebei Province (JZX2023018)
  • Department of Education of Hebei Province (QN2024104)
  • Hebei University (QNTD202401)
  • National Natural Science Foundation of China (32101371)

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