Plasmid-mediated bioaugmentation of sequencing batch reactors for enhancement of 2,4-dichlorophenoxyacetic acid removal in wastewater using plasmid pJP4.

Plasmid-mediated bioaugmentation was demonstrated using sequencing batch reactors (SBRs) for enhancing 2,4-dichlorophenoxyacetic acid (2,4-D) removal by introducing Cupriavidus necator JMP134 and Escherichia coli HB101 harboring 2,4-D-degrading plasmid pJP4. C. necator JMP134(pJP4) can mineralize and grow on 2,4-D, while E.

Transfer of plasmid pJP4 from Escherichia coli and Pseudomonas putida to bacteria in activated sludge developed under different sludge retention times.

To add the knowledge on the plasmid-mediated bioaugmentation in the activated sludge process, conjugative transfer of a self-transmissible, broad host range, mercury resistance, and partial 2,4-dichlorophenoxyactic acid (2,4-D)-degrading plasmid pJP4 from Escherichia coli HB101 or Pseudomonas putida KT2440 to activated sludge bacteria were examined by filter mating. Activated sludge samples were collected from an actual wastewater treatment plant and laboratory reactors operated under different sludge retention times (SRTs) of 5, 10, and 15 days. Transfer of pJP4 was observed in all combinations of donor and activated sludge (recipient) with the transfer frequency from 6.