Identification of acetaminophen degrading microorganisms in mixed microbial communities using 13C-DNA stable isotope probing

The high frequency of acetaminophen (APAP) detection in water bodies around the world increases the risk to the global environment. A lot of work has concentrated on isolating and identifying the culturable APAP degraders for understanding of the microbiota and their ecophysiology, which greatly underrated the diversity of organisms. Here, 13C-DNA stable isotope probing (DNA-SIP) was applied for the first time to identify microorganisms involved in APAP metabolism under conditions close to in situ from three mixed microbial communities collected in lab-scale nitrification systems. Based on DNA-SIP, Achromobacter (oligotype ATAA), Alicycliphilus (oligotype GTTCG) and Thauera (oligotype GAAACTTTCA) were identified as the key APAP degrading bacteria in the floc sludge, granular sludge and biofilm reactors, respectively, with the relative abundance of 43.20%, 10.12% and 12.60%. Moreover, Leucobacter, Achromobacter, Alicycliphilus, Thauera, Microbacterium and Lactobacillus were found, for the first time, to be directly responsible for APAP biodegradation. However, Achromobacter, Lactobacillus and Alicycliphilus were linked to spread resistance genes (intI1, sul2, qacEdta1-02 and qacH-01). The results highlight that Acinetobacter, Leucobacter, Thauera and Microbacterium could be recommended as bioaugmentation strains for the treatment of wastewater contaminated with APAP. Ultimately, the information acquired in this study could add to the current knowledge on microorganisms degrading APAP and accelerate the implementation of biofortification processes to achieve APAP removal.