CYANIDE UTILIZATION IN PSEUDOMONAS-FLUORESCENS NCIMB-11764 INVOLVES APUTATIVE SIDEROPHORE

Cyanide utilization in P. fluorescens NCIMB 11764 requires the inducti on of cyanide oxygenase. The enzyme is induced during growth on cyanid e as the sole nitrogen source or when cyanide is added to stationary-p hase cells grown on limiting ammonia, however, enzyme induction and cy anide degradation were found to occur non-concomitantly. Cyanide remov al by chloramphenicol-treated cells and a mutant strain (JL102) defect ive in cyanide oxygenase were also observed. We now report a non-enzym atic mechanism for cyanide biotransformation by an iron-chelating spec ies identified as a putative siderophore. Partially purified sideropho re preparations removed cyanide at initial rates as high as 7.6 mmol m in(-1) mg(-1). The reaction product was further shown to be enzymatica lly oxidized to NH3 (and CO2) and also supported growth. The results i ndicate that both cyanide oxygenase and a putative siderophore compone nt are involved in cyanide utilization.