title: Impacts of gene bioaugmentation with pJP4-harboring bacteria of 2,4-D-contaminated soil slurry on the indigenous microbial community.
abstract: Gene bioaugmentation is a bioremediation strategy that enhances biodegradative potential via dissemination of degradative genes from introduced microorganisms to indigenous microorganisms. Bioremediation experiments using 2,4-dichlorophenoxyacetic acid (2,4-D)-contaminated soil slurry and strains of Pseudomonas putida or Escherichia coli harboring a self-transmissible 2,4-D degradative plasmid pJP4 were conducted in microcosms to assess possible effects of gene bioaugmentation on the overall microbial community structure and ecological functions (carbon source utilization and nitrogen transformation potentials). Although exogenous bacteria decreased rapidly, 2,4-D degradation was stimulated in bioaugmented microcosms, possibly because of the occurrence of transconjugants by the transfer of pJP4. Terminal restriction fragment length polymorphism analysis revealed that, although the bacterial community structure was disturbed immediately after introducing exogenous bacteria to the inoculated microcosms, it gradually approached that of the uninoculated microcosms. Biolog assay, nitrate reduction assay, and monitoring of the amoA gene of ammonia-oxidizing bacteria and nirK and nirS genes of denitrifying bacteria showed no irretrievable depressive effects of gene bioaugmentation on the carbon source utilization and nitrogen transformation potentials. These results may suggest that gene bioaugmentation with P. putida and E. coli strains harboring pJP4 is effective for the degradation of 2,4-D in soil without large impacts on the indigenous microbial community.
authors.affiliation: Division of Sustainable Energy and Environmental Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan. inoue@wb.see.eng.osaka-u.ac.jp
authors.forename: Daisuke
authors.initials: D
authors.lastname: Inoue
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Tsutsui
authors.forename: Kazunari
authors.initials: K
authors.lastname: Sei
authors.forename: Satoshi
authors.initials: S
authors.lastname: Soda
authors.forename: Masanori
authors.initials: M
authors.lastname: Fujita
authors.forename: Michihiko
authors.initials: M
authors.lastname: Ike
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D001673:Biodegradation, Environmental / Q000187:drug effects; D002244:Carbon / Q000494:pharmacology; D016000:Cluster Analysis; D003227:Conjugation, Genetic / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D058458:Nitrogen Cycle / Q000187:drug effects; D010084:Oxidation-Reduction / Q000187:drug effects; D010957:Plasmids / Q000235:genetics; D012150:Polymorphism, Restriction Fragment Length / Q000235:genetics; D016958:Pseudomonas putida / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012722:Sewage / Q000382:microbiology*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D009566:Nitrates; D012722:Sewage; D012989:Soil Pollutants; D015084:2,4-Dichlorophenoxyacetic Acid; D002244:Carbon