Microbial degradation of thidiazuron and its photoproduct

Area of Science:

• Environmental Microbiology
• Biochemistry

Background:

• Thidiazuron is a widely used cotton defoliant.
• Understanding its environmental fate and degradation pathways is crucial.

Purpose of the Study:

• To investigate the microbial degradation of thidiazuron and its photoproduct, photothidiazuron.
• To identify the microorganisms and metabolites involved in these degradation processes.

Main Methods:

• Incubation of thidiazuron and photothidiazuron with soil and thirteen microbial species.
• Analysis of degradation products using chromatographic and spectroscopic techniques.
• Use of radiolabeled thidiazuron (thidiazuron-aniline-14C) to trace metabolic pathways.

Main Results:

• Aspergillus versicolor, Torula rosea, and Flavobacter sp. showed significant activity in degrading thidiazuron, yielding phenylurea and unknown water-soluble metabolites.
• Aspergillus versicolor and Penicillium cyclopium were most effective in degrading photothidiazuron.
• Metabolites identified included 4-Hydroxyphenylphotothidiazuron (from A. versicolor) and phenylurea (from P. cyclopium).
• Oscillatoria sp. converted radiolabeled thidiazuron to carbon dioxide, indicating its use as an energy source.

Conclusions:

• Several soil microorganisms possess the capability to degrade thidiazuron and photothidiazuron.
• The degradation pathways involve the formation of various organosoluble and water-soluble metabolites, including phenylurea.
• Certain microorganisms can utilize thidiazuron as a carbon and energy source.