Biodegradation of cyanides, cyanates and thiocyanates to ammonia and carbon dioxide by immobilized cells of Pseudomonas putida

Pseudomonas putida utilizes cyanide as the sole source of carbon and nitrogen. Agar, alginate, and carrageenan were screened as the encapsulating matrices for P. putida. Alginate-immobilized cells of P. putida degraded sodium cyanide (NaCN) more efficiently than non-immobilized cells or cells immobilized in agar or carrageenan. The end products of biodegradation of cyanide were identified as ammonia (NH₃) and carbon dioxide (CO₂). These products changed the medium pH. In bioreactors, the rate of cyanide degradation increased with an increase in the rate of aeration. Maximum utilization of cyanide was observed at 200 ml min⁻¹ of aeration. Immobilized cells of P. putida degraded cyanides, cyanates and thiocyanates to NH₃ and CO₂. Use of Na[¹⁴C]-CN showed that 70% of carbon of Na[¹⁴C]-CN was converted into ¹⁴CO₂ and only 10% was associated with the cell biomass. The substrate-dependent kinetics indicated that the K _m and V _max values of P. putida for the substrate, NaCN were 14 mM and 29 nmol of oxygen consumed mg protein⁻¹ min⁻¹ respectively. Received 29 January 1996/ Accepted in revised form 19 September 1997