title: Bioaugmentation of aerobic sludge granules with a plasmid donor strain for enhanced degradation of 2,4-dichlorophenoxyacetic acid.
abstract: Aerobic sludge granules pre-grown on glucose were bioaugmented with a plasmid pJP4 carrying strain Pseudomonas putida SM1443 in a fed-batch microcosm system and a lab-scale sequencing batch reactor (SBR) to enhance their degradation capacity to 2,4-dichlorophenoxyacetic acid (2,4-D). The fed-batch test results showed that the bioaugmented aerobic granule system gained 2,4-D degradation ability faster and maintained a more stable microbial community than the control in the presence of 2,4-D. 2,4-D at the initial concentration of about 160 mg/L was nearly completely removed by the bioaugmented granule system within 62 h, while the control system only removed 26% within 66 h. In the bioaugmented SBR which had been operated for 90 days, the seeded aerobic granules pre-grown on glucose successfully turned into 2,4-D degrading granules through bioaugmentation and stepwise increase of 2,4-D concentration from 8 to 385 mg/L. The granules showed a compact structure and good settling ability with the mean diameter of about 450 microm. The degradation kinetics of 2,4-D by the aerobic granules can be described with the Haldane kinetics model with V(max)=31.1 mg 2,4-D/gVSS h, K(i)=597.9 mg/L and K(s)=257.3 mg/L, respectively. This study shows that plasmid mediated bioaugmentation is a feasible strategy to cultivate aerobic granules degrading recalcitrant pollutants.
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China. xchquan@bnu.edu.cn
authors.forename: Xiang-chun
authors.initials: XC
authors.lastname: Quan
authors.forename: Hua
authors.initials: H
authors.lastname: Tang
authors.forename: Wei-cong
authors.initials: WC
authors.lastname: Xiong
authors.forename: Zhi-feng
authors.initials: ZF
authors.lastname: Yang
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D000332:Aerobiosis; D001673:Biodegradation, Environmental; D019149:Bioreactors; D002876:Chromosomes, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D004785:Environmental Pollutants / Q000378:metabolism*; D007700:Kinetics; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D010957:Plasmids / Q000235:genetics*; D011489:Protein Denaturation; D016958:Pseudomonas putida / Q000235:genetics* / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012722:Sewage / Q000382:microbiology*
chemical_list: D004785:Environmental Pollutants; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D015084:2,4-Dichlorophenoxyacetic Acid