Characterization of a Novel Amidase and Catabolic Pathway in Paraburkholderia sp. AP1-9 Involved in Acetaminophen Biodegradation

Abstract Acetaminophen (APAP) is a ubiquitous pharmaceutical contaminant frequently detected in agricultural environments and crop produce due to its extensive consumption and continuous release. Although microbial degradation is a major pathway for APAP removal, the molecular mechanisms underlying APAP catabolism in Paraburkholderia remain unexplored. In this study, an efficient APAP-degrading bacterium, Paraburkholderia sp. AP1-9, was isolated from activated sludge and characterized through genomic, biochemical, and metabolite analyses. Genome analysis identified acdH, encoding a previously uncharacterized amidase with limited sequence similarity to reported APAP amidases. Functional characterization confirmed that AcdH catalyzed APAP hydrolysis to 4-aminophenol, while molecular docking suggested K81, S159, and S183 as putative catalytic residues. Homology searches identified 4664 putative homologs across diverse bacterial taxa, with the greatest enrichment in Streptomycetaceae. Collectively, these findings elucidate the molecular basis of APAP degradation in Paraburkholderia and expand understanding of APAP amidase diversity and evolution.