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.
Original language | English |
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Pages (from-to) | 501-512 |
Number of pages | 12 |
Journal | Biodegradation |
Volume | 16 |
Issue number | 6 |
DOIs | |
State | Published - Dec 2005 |
Externally published | Yes |
Funding
The authors would like to thank Dr. James Cornette for generously supplying soil samples for this research. Funding for this research project was provided by The United States Air Force Office of Scientific Research (AASERT Award) FA9620-95-0400 and the Dow Foundation SPHERE Award to GSS.
Keywords
- 2,4,5-T
- 2,4,5-Trichlorophenoxyacetic acid
- 2,4-D
- 2,4-Dichlorophenoxyacetic acid
- Agent Orange