Uptake and Dechlorination of an Organochlorine Fungicide, Tetrachloroisophthalonitrile, Daconil, by Some Soil Fungi

Fungi tolerant to an organochlorine fungicide, tetrachloroisophthalonitrile (TCPN), was selected and isolated from various soil samples, and examined for the activity to metabolize TCPN. The population of tolerant fungi was extremely large in the plastic house - soil on which TCPN has been used for six years to control diseases. This is probably due to the change of soil microflora owing to the decline of TCPN-sensitive competitors. Many tolerant fungi took up TCPN very rapidly from culture filtrate. Of ten tolerant isolates tested, two isolates, C-F- I and V-P-5, were found to metabolize TCPN. The metabolite was isolated in pure form by preparative TLC, and identified as trichloroisophthalonitrile by mass spectrometry. C-F-1 was identified as Aspergillus luchuensis and V-P-5 as Penicillium godlewskii. Namely, these soil fungi dechlorinate from tetrachloroisophthalontrile to trichloroisophthalonitrile.