Involvement of Microorganisms in Accelerated Degradation of EPTC in Soil

Accelerated EPTC (S-ethyl dipropylcarbamothioate) degradation was confirmed in a mixed culture of microorganisms derived from a soil with enhanced degradation (history soil) by using ¹⁴C-labeled EPTC. The antibacterial agent chloramphenicol (D-(-)-threo-2,2-dichloro-N-[β-hydroxy-a-(hydroxymethyl)-p-nitrophenethyl]acetamide) markedly suppressed ¹⁴CO₂evolution while the antifungal agent cycloheximide (4-[(2R)-2-((1S,3S,5S)-3,5-dimethyl-2-oxocyclohexyl)-2-hydroxyethyl]glutarimide) did not, suggesting that soil bacteria play a significant role in enhanced EPTC degradation. A fast EPTC bacterial degrader (FD1) strain and a slower one (SD1), which were isolated by a soil enrichment technique from a history soil, were capable of utilizing EPTC as a sole carbon source. Vernolate (Spropyl dipropylcarbamothioate), butylate (S-ethyl bis(2-methylpropyl)carbamothioate), or cycloate (S-ethyl cyclohexylethylcarbamothioate) were also degraded by these bacteria in a pattern similar to that in a soil with enhanced degradation. Inoculation of nonhistory soil with FD1 strain induced accelerated degradation of the herbicide in the soil at rates similar to those in field soils exhibiting EPTC accelerated degradation.