title: Natural selection for 2,4,5-trichlorophenoxyacetic acid mineralizing bacteria in agent orange contaminated soil.
abstract: Agent Orange contaminated soils were utilized in direct enrichment culture studies to isolate 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid (2,4-D) mineralizing bacteria. Two bacterial cultures able to grow at the expense of 2,4,5-T and/or 2,4-D were isolated. The 2,4,5-T degrading culture was a mixed culture containing two bacteria, Burkholderia species strain JR7B2 and Burkholderia species strain JR7B3. JR7B3 was able to metabolize 2,4,5-T as the sole source of carbon and energy, and demonstrated the ability to affect metabolism of 2,4-D to a lesser degree. Strain JR7B3 was able to mineralize 2,4,5-T in pure culture and utilized 2,4,5-T in the presence of 0.01% yeast extract. Subsequent characterization of the 2,4-D degrading culture showed that one bacterium, Burkholderia species strain JRB1, was able to utilize 2,4-D as a sole carbon and energy source in pure culture. Polymerase chain reaction (PCR) experiments utilizing known genetic sequences from other 2,4-D and 2,4,5-T degrading bacteria demonstrated that these organisms contain gene sequences similar to tfdA, B, C, E, and R (Strain JRB1) and the tftA, C, and E genes (Strain JR7B3). Expression analysis confirmed that tftA, C, and E and tfdA, B, and C were transcribed during 2,4,5-T and 2,4-D dependent growth, respectively. The results indicate a strong selective pressure for 2,4,5-T utilizing strains under field condition.
authors.affiliation: Monsanto, Mailstop U4C, 800 North Lindbergh, St. Louis, MO 63167, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Rice
authors.forename: F M
authors.initials: FM
authors.lastname: Menn
authors.forename: A G
authors.initials: AG
authors.lastname: Hay
authors.forename: J
authors.initials: J
authors.lastname: Sanseverino
authors.forename: G S
authors.initials: GS
authors.lastname: Sayler
mesh_terms: D015085:2,4,5-Trichlorophenoxyacetic Acid / Q000378:metabolism*; D015084:2,4-Dichlorophenoxyacetic Acid / Q000378:metabolism*; D000075182:Agent Orange; D001483:Base Sequence; D001673:Biodegradation, Environmental; D019117:Burkholderia / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D003678:Defoliants, Chemical / Q000378:metabolism*; D005798:Genes, Bacterial; D007700:Kinetics; D008903:Minerals / Q000378:metabolism; D000072317:Polychlorinated Dibenzodioxins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D003678:Defoliants, Chemical; D008903:Minerals; D000072317:Polychlorinated Dibenzodioxins; D012989:Soil Pollutants; D015084:2,4-Dichlorophenoxyacetic Acid; D000075182:Agent Orange; D015085:2,4,5-Trichlorophenoxyacetic Acid