Degradation of ferrous(II) cyanide complex ions by Pseudomonas fluorescens

Degradation of ferrous(II) cyanide complex (ferrocyanide) ions by free cells of P. fluorescens in the presence of glucose and dissolved oxygen was investigated as a function of initial pH, initial ferrocyanide and glucose concentrations and aeration rate in a batch fermenter. The microorganism used the ferrocyanide ions as the sole source of nitrogen. The ferrocyanide biodegradation rate was 30.7 mg g⁻¹ h⁻¹ under the conditions of initial pH: 5, stirring rate: 150 rpm, aeration rate: 0.15 vvm, initial ferrous(II) cyanide complex ion and glucose concentrations: 100 mg l⁻¹ and 0.465 g l⁻¹, respectively. The culture utilized glucose as the main substrate following the non-competitive toxic component inhibition model in the presence of 100 mg l⁻¹ initial ferrous(II) cyanide complex ion concentration. The inhibition of ferrous(II) cyanide complex ions as a secondary substrate began at very low concentrations. A mathematical model, based on non-competitive substrate inhibition was used to describe the inhibitory effect of ferrous(II) cyanide complex ions on the growth of microorganism and the best fitted model parameters were determined by non-linear regression techniques.