Genetic bioaugmentation with triclocarban-catabolic plasmid effectively removes triclocarban from wastewater

Triclocarban, one of the emerging pollutants, has been accumulating, and it is frequently detected in wastewater. Due to its toxicity and persistence, the efficient removal of triclocarban from wastewater systems is challenging. Genetic bioaugmentation with transferable catabolic plasmids has been considered to be a long-lasting method to clean up pollutants in continuous flow wastewater treatment systems. In this study, bioaugmentation with Pseudomonas putida KT2440, harboring the transferrable triclocarban-catabolic plasmid pDCA-1-gfp-tccA2, rapidly converted 50 mu M triclocarban in wastewater into 3,4-dichloroaniline and 4-chloroaniline, which are further mineralized more easily. RT-qPCR results showed that the ratio of the copy number of pDCA-1-gfp-tccA2 to the cell number of strain KT2440 gradually increased during genetic bioaugmentation, suggesting horizontal transfer and proliferation of the plasmid. By using DNA stable isotope probing (SIP) and amplicon sequencing, OTU86 (Escherichia-Shigella), OTU155 (Citrobacter), OTU5 (Brucella), and OTU15 (Enterobacteriaceae) were found to be the potential recipients of the plasmid pDCA-1-gfp-tccA2 in the wastewater bacterial community. Furthermore, three transconjugants in the genera of Escherichia, Citrobacter, and Brucella showing triclocarban-degrading abilities were isolated from the wastewater. This study develops a new method for removing triclo-carban from wastewater and provides insights into the environmental behavior of transferrable catabolic plas-mids in bacterial community in wastewater systems.

Automated summary

This study demonstrates the efficient removal of triclocarban from wastewater using genetic bioaugmentation with Pseudomonas putida KT2440, which harbors a transferable triclocarban-catabolic plasmid. The study also provides insights into the horizontal transfer and proliferation of the plasmid in the wastewater bacterial community, and identifies potential recipients of the plasmid in the community. Isolation of transconjugants with triclocarban-degrading abilities further confirms the effectiveness of the bioaugmentation method.