Factors affecting the biodegradation of cyanide by Burkholderia cepacia strain C-3

Abstract

The utilization of cyanide as a nitrogen source for growth in a liquid minimal medium by Burkholderia cepacia strain C-3 isolated from soil was demonstrated. The effects of various parameters on the biodegradation of cyanide by the strain were investigated. Growth at the expense of cyanide occurred over a pH range from 8 to 10, and was optimal at pH 10. Growth and cyanide biodegradation were optimal at 30 degrees C. The presence of Cu2+ or Fe2+ in the liquid medium at a concentration of 1 mM inhibited both the growth of the bacterium and its cyanide degradation. The effects of Ni2+ and Co2+, and to a lesser extent Mn2+ and Mo2+, on cyanide degradation rate were concentration dependent. Addition of the cyanide-containing waste contaminants ethanol and methanol reduced the cyanide utilization of the isolate, but phenol was completely inhibitory. Microbial depletion of cyanide occurred even in the presence of other organic and inorganic nitrogen sources. Fructose, glucose, and mannose were the preferred carbon sources for cyanide biodegradation. The highest rate of cyanide degradation by B. cepacia C-3, 1.85 mg CN h(-1), was observed with 0.25% (w/v) fructose; the degradation rate decreased progressively thereafter with increasing fructose concentration.