title: Plasmid-mediated bioaugmentation of sequencing batch reactors for enhancement of 2,4-dichlorophenoxyacetic acid removal in wastewater using plasmid pJP4.
abstract: 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. coli HB101(pJP4) cannot assimilate 2,4-D because it lacks the chromosomal genes to degrade the intermediates. The SBR with C. necator JMP134(pJP4) showed 100 % removal against 200 mg/l of 2,4-D just after its introduction, after which 2,4-D removal dropped to 0 % on day 7 with the decline in viability of the introduced strain. The SBR with E. coli HB101(pJP4) showed low 2,4-D removal, i.e., below 10 %, until day 7. Transconjugant strains of Pseudomonas and Achromobacter isolated on day 7 could not grow on 2,4-D. Both SBRs started removing 2,4-D at 100 % after day 16 with the appearance of 2,4-D-degrading transconjugants belonging to Achromobacter, Burkholderia, Cupriavidus, and Pandoraea. After the influent 2,4-D concentration was increased to 500 mg/l on day 65, the SBR with E. coli HB101(pJP4) maintained stable 2,4-D removal of more than 95 %. Although the SBR with C. necator JMP134(pJP4) showed a temporal depression of 2,4-D removal of 65 % on day 76, almost 100 % removal was achieved thereafter. During this period, transconjugants isolated from both SBRs were mainly Achromobacter with high 2,4-D-degrading capability. In conclusion, plasmid-mediated bioaugmentation can enhance the degradation capability of activated sludge regardless of the survival of introduced strains and their 2,4-D degradation capacity.
authors.affiliation: Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka, 565-0871, Japan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tsutsui
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Anami
authors.forename: Masami
authors.initials: M
authors.lastname: Matsuda
authors.forename: Kurumi
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Inoue
authors.forename: Kazunari
authors.initials: K
authors.lastname: Sei
authors.forename: Satoshi
authors.initials: S
authors.lastname: Soda
authors.forename: Michihiko
authors.initials: M
authors.lastname: Ike
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000302:isolation & purification*; D001483:Base Sequence; D019149:Bioreactors; D020118:Cupriavidus necator / Q000378:metabolism; D017931:DNA Primers; D004926:Escherichia coli / Q000378:metabolism; D010957:Plasmids; D060888:Real-Time Polymerase Chain Reaction; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D015084:2,4-Dichlorophenoxyacetic Acid; D017931:DNA Primers; D062065:Wastewater; D014874:Water Pollutants, Chemical