TRANSFORMATION OF THE INSECTICIDE TEFLUBENZURON BY MICROORGANISMS

Abstract

Transformation of teflubenzuron, the active component in the insecticide commercialized as Nomolt, by soil microorganisms was studied. It was shown that microorganisms, belonging to Bacillus, Alcaligenes, Pseudomonas and Acinetobacter genera are capable to perform the hydrolytic cleavage of the phenylurea bridge of teflubenzuron in different positions, especially active was Bacillus brevis 625. The structure of the intermediates formed was established using TLC, HPLC, mass-spectrometry and ¹⁹F NMR techniques. It was shown that for a dose range of 537–132 μM and upon 12 days of fermentation about 30 % of the teflubenzuron was modified. About 10–15 % was transformed into 2,6-difluorobenzamide, 3–5 % into 2,6-difluorobenzoic acid, 10–12 % into 2,4-difluoro-3,5-dichloro-aniline. The late compound gave rise to formation of a condensed compound, identified as 1,2-bis(2,4-difluoro-3,5-dichlorophenyl)urea with molecular mass of 420.The results obtained indicate degradation of teflubenzuron by soil microorganisms to be a process to be mediated by microbial consortia, and starting with hydrolysis of the phenylurea bridge by several bacterial species. Subsequent further degradation of the aromatic degradation products has to be mediated by other strains known to be capable of degradation of halogenated aromatics.

Keywords:

• Teflubenzuron
• Conversion
• Microorganisms
• Intermediates

ACKNOWLEDGMENTS

The authors wish to acknowledge the financial support provided by NWO (Grant 047–007–021) and EC (Grant ICA2-CT-2000-10006). The authors are very thankful to Tatiana Platonova for very skillful technical assistance during this investigation.