Multiple catabolism contributes to biodegradation of phthalate-based plasticizers in Acinetobacter baumannii

Phthalates (PAEs) have been widely used as plasticizers in the production of plastics. Unfortunately, PAEs released into the environment during plastic aging pose a threat to human life and health. Although microbial biodegradation of PAEs has proven to be an emerging bioremediation approach to modern plastic pollution, the microbial catabolism of PAEs remains elusive. Here, we isolate a PAE-degrading bacterium (identified as Acinetobacter baumannii EMB-1) from crude oil wastewater using Di-n-octylo-phthalate (DnOP) as the sole carbon source and unravel the PAE degradation pathway through a multi-omics approach. We observe that A. baumannii EMB-1 grows well both at low (2-5 g/L) and high (20-50 g/L) concentrations of DnOP but cannot grow on glucose due to a lack of hexokinase. The multi-omics analyses reveal that A. baumannii EMB-1 employs multiple catabolic pathways, including phenylacetic acid degradation, protocatechuic acid (PCA) degradation, and benzoate degradation, which synergistically degrade DnOP. Interestingly, phenylacetate and benzoate catabolism is directly linked to the tricarboxylic acid cycle, whereas partial PCA degradation is used to generate substrates for synthesizing aromatic amino acids. Our findings advance the understanding of microbial PAE catabolism and expand microbial resources that could benefit biological upcycling and bioremediation of recalcitrant phthalate-based plasticizers.