Natural selection for 2,4,5-trichlorophenoxyacetic acid mineralizing bacteria in agent orange contaminated soil |
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Authors: | J?F?Rice F?-M?Menn A?G?Hay J?Sanseverino Email author" target="_blank">G?S?SaylerEmail author |
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Institution: | (1) Present address: Monsanto, 800 North Lindbergh, Mailstop U4C, St. Louis, MO 63167, USA;(2) Present address: Center for Environmental Biotechnology and the Department of Microbiology, The University of Tennessee, 676 Dabney Hall, Knoxville, TN 37996-1605, USA;(3) Department of Microbiology, Cornell University, Ithaca, NY 14853, USA |
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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, Burkholderiaspecies 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. |
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Keywords: | Agent Orange 2 4-D 2 4-dichlorophenoxyacetic acid 2 4 5-T 2 4 5-trichlorophenoxyacetic acid |
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