Soil and water samples, which were collected into an Artisanal Small-scale Gold Mining (ASGM) catchment area in Burkina Faso, present a high value of Free Cyanide (F-CN) concentration. The cyanide degrading bacteria (CDB) were detected in all samples. These indigenous microorganisms could be able to degrade F-CN. Factors influencing the cyanide biodegradation and its kinetics were studied for controlling the bioremediation application in-situ and/or ex-situ. Consortium bacteria comes from these samples was cultivated in the medium containing 60 mg F-CN L-1 under various conditions. pH, carbon and nitrogen nutrients source were varied. The cyanide removal efficiency was respectively 99.8 %, 99.74 %, and 99.82 % at pH 9.5, in the presence of glucose as carbon sources, and in the presence of ammonium sulfate as nitrogen source during 24 hours. The Michaelis–Menten kinetics was determined for the test under different concentration of cyanide solution from 10 to 80 mg F-CN L-1 and Total Cyanide (T-CN) L-1. Realistic values of the half-saturation constant, KM, were between 3 and 19 mg F-CN L-1 and between 4 and 18 mg T-CN L-1. The maximum metabolic capacity, Vmax, was respectively around 0.97 mg F-CN L-1 mn-1 and 0.93 mg T-CN L-1 mn-1. The consortium bacteria that used have a capacity to degrade cyanide. The cyanide degradation by each species that formed the bacteria consortium should be investigated for having more precision on the enzymatic kinetics model.
The Swiss Cooperation Agency was funded this research under the grant number 81016359/1.