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Soil Science Society of America Journal Abstract -

Metabolism of Carbamothioate Herbicide, EPTC, by Rhodococcus Strain JE1 Isolated from Soil


This article in SSSAJ

  1. Vol. 59 No. 4, p. 1071-1077
    Received: Dec 15, 1994

    * Corresponding author(s): dick.5@osu.edu
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  1. R. O. Ankumah,
  2. W. A. Dick  and
  3. G. McClung
  1. Dep. of Agricultural Sciences, Tuskegee Univ., Tuskegee, AL 36088
    Dep. of Agronomy, Ohio State Univ., 1680 Madison Ave., Wooster, OH 44691



Biodegradation of the her bicide EPTC (s-ethyl dipropylcarbamothioate) at greatly enhanced rates, which may lead to poor weed control, can occur in soil after successive annual applications. The mechanisms of EPTC degradation by a strain of Rhodococcus sp. (designated JE1) previously isolated from soil were evaluated. Degradation of 14C-labeled (at the 1-propyl position) and unlabeled EPTC was followed by thin layer chromatogaphy and gas chromatography-mass spectrometry. The N-depropyl EPTC and EPTC sulfoxide were identified as initial metabolites formed, apparently via hydroxylation of the α-propyl C and oxidation of the S atom of EPTC, respectively. Other products of EPTC degradation identified were propionaldehyde, s-ethyl carbonothioic acid, s-methyl carbonothioic acid, and traces of propylamine. It is proposed that the soil isolate Rhodococcus JE1 degrades EPTC via either an initial hydroxylation or sulfoxidation reaction, producing metabolites that can be further mineralized to form CO2. The α-propyl hydroxylation reaction, however, is thought to be the dominant pathway whereby degradation of EPTC occurs in soil at enhanced rates.

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