Reductive transformation of dieldrin under anaerobic sediment culture.
A pathway of dieldrin transformation to aldrin by epoxide reduction was found in this study. Investigation of dieldrin degradation under anaerobic conditions was performed with a mixed culture containing indigenous microorganisms obtained from sediment of the Er-Jen River in Taiwan. During the incubation, the transformation of dieldrin to aldrin was analyzed by GC-ECD and GC-MS. Effects of incubation factors including dieldrin concentrations, incubation temperatures and kinds of carbon sources on the degradation of dieldrin were also studied. Original concentrations (from 0.5 to 10 microg ml(-1)) of dieldrin affect the transformation rate of dieldrin, and lower concentrations indicated the higher degradation rates. But once the concentration higher than 100 microg ml(-1), almost no degradation occurred. The optimal temperature for degradation in mixed culture was found at 40 degrees C in this study. Dieldrin transformation rates varied with the type of major carbon sources in the mixed culture and were in order of yeast extract > sodium acetate > glucose. In addition, the denaturing gradient gel electrophoresis (DGGE) fingerprint revealed that four microbials evolved in dieldrin-amended cultures, but not in the dieldrin-free cultures. Partial sequence of 16S rDNA for these four organisms exhibited 94-99% similarity to those of genera Clostridium, Acidaminobacter and an uncultured bacterial group. These results suggest that the four microbials might promote the dieldrin transformation.
Chiu
Tzu-Chuan
TC
Department of Agricultural Chemistry, National Taiwan University, 1, Sec. 4, Taipei 10617, Taiwan, ROC.
Yen
Jui-Hung
JH
Hsieh
Yar-Ning
YN
Wang
Yei-Shung
YS
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D001711:Biotransformation; D002849:Chromatography, Gas; D003470:Culture Media; D004026:Dieldrin / Q000378:metabolism*; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D005947:Glucose / Q000737:chemistry; D010084:Oxidation-Reduction; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D045483:Rivers; D019346:Sodium Acetate / Q000737:chemistry; D012988:Soil Microbiology; D013624:Taiwan; D013696:Temperature; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D015003:Yeasts / Q000737:chemistry
D003470:Culture Media; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D019346:Sodium Acetate; D004026:Dieldrin; D005947:Glucose