Rich Efficient Short-Chain Phthalate Esters-Degrading Bacteria and Their Degradation Mechanisms in Recycled Plastic Wastewater Treatment Plant

Microbial degradation of phthalate esters (PAEs) is regarded as a highly promising green remediation strategy for PAE-contamination, but it still remains constrained by the scarcity of efficient microbial resources capable of degrading PAEs completely under complex conditions. This study systematically explored microbial resources resistant to dimethyl phthalate (DMP)/dibutyl phthalate (DBP) stress along with the putative degradation mechanisms in recycled plastic sewage treatment plants through high-throughput sequencing, DMP/DBP-degrading bacteria screening, and whole-genome sequencing of representative efficient DBP-degrading strains. High-throughput sequencing result revealed substantial enrichment of PAEs-degrading bacteria in activated sludge exposed to 500 mg L−1 DMP/DBP. Further analysis demonstrated that the recycled plastic sewage treatment plant harbored rich culturable DMP/DBP-degrading bacteria, comprising 19 genera and 27 species of DMP-degrading bacteria, as well as 11 genera and 20 species of DBP-degrading bacteria. Notably, strain SWLYDMP 33, a potential novel species, along with 11 genera such as Paenirhodobacter, Ciceribacter, and Neorhizobium has been scarcely reported in association with PAEs degradation. Given its affiliation with a dominant genus and its superior broad-spectrum degradation performance, the representative efficient DBP-degrading strain SWLYDBP 51 was selected for whole-genome sequencing. Genome annotation of strain SWLYDBP 51 uncovered a wealth of functional genes implicated in DBP metabolism, and the putative complicated DBP degradation pathways were reconstructed, suggesting that SWLYDBP 51 might possess the genetic capacity for effectively degrading DBP under diverse environmental conditions. Overall, this study provided abundant efficient microbial resources and a theoretical reference for the bioremediation of PAEs contamination.