Anaerobic degradation of 2,4-dichlorophenoxyacetic acid by Thauera sp. DKT
Thauera sp. strain DKT isolated from sediment utilized 2,4-dichlorophenoxyacetic acid (2,4D) and its relative compounds as sole carbon and energy sources under anaerobic conditions and used nitrate as an electron acceptor. The determination of 2,4D utilization at different concentrations showed that the utilization curve fitted well with the Edward model with the maximum degradation rate as 0.017 ± 0.002 mM/day. The supplementation of cosubstrates (glucose, acetate, sucrose, humate and succinate) increased the degradation rates of all tested chemical substrates in both liquid and sediment slurry media. Thauera sp. strain DKT transformed 2,4D to 2,4-dichlorophenol (2,4DCP) through reductive side-chain removal then dechlorinated 2,4DCP to 2-chlorophenol (2CP), 4-chlorophenol (4CP) and phenol before complete degradation. The relative degradation rates by the isolate in liquid media were: phenol > 2,4DCP > 2CP > 4CP > 2,4D ≈ 3CP. DKT augmentation in sediment slurry enhanced the degradation rates of 2,4D and chlorophenols. The anaerobic degradation rates in the slurry were significantly slower compared to the rates in liquid media.
KeywordsThauera sp. strain DKT 2,4-Dichlorophenoxyacetic acid Edward model Sediment slurry Augmentation Anaerobic degradation
This study was carried out at the same time and same place as the determination of anaerobic degradation of chloroanilines. We are very thankful to our families, especially my wife Nguyen Thi Oanh (Dong Thap University, Viet Nam) for all the support provided to do this study.
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