2,4-DICHLOROPHENOXYACETIC ACID DETECTION USING 2,4-DICHLOROPHENOXYACETIC ACID ALPHA-KETOGLUTARATE DIOXYGENASE

The 2,4-dichlorophenoxy acid (2,4-D) alpha-ketoglutarate dioxygenase g ene tfdA of Alcaligenes eutrophus pJP4 derivative plasmid pRO101 was c loned in pBluescript SK+ and expressed in Escherichia coli DH5 alpha a t a high level. Cell-free extract of the recombinant organism could co nvert 2,4-dichlorophenoxyacetic acid into 2,4-dichlorophenol (DCP). Pr oduction of DCP was indicated by a color reaction using 4-amino-antipy rine and could be used as an assay for the presence of 2,4-D. After st orage at room temperature for 3 months, cell-free extracts prepared fr om the recombinant organism and air-dried in filter paper bags still c onverted 2,4-D to DCP. Reaction conditions for conversion of 2,4-D to DCP were optimized, and the enzymatic reaction kinetics were determine d. It appears feasible to use the recombinant-produced enzyme for an i nexpensive 2,4-D assay.