Biodegradation of Cyanide under Alkaline Conditions by a Strain of Pseudomonas Putida Isolated from Gold Mine Soil and Optimization of Process Variables through Response Surface Methodology (RSM)

Abstract

In regard to highly poisonous effects of cyanide ion, concerns have been focused recently on treatment of such compounds in different ways. Four bacterial strains (C1-C4) capable of using cyanide as nitrogen source were isolated from contaminated gold mine soil samples under alkaline conditions at 30 °C, pH 9.5-10.5, and agitation speed 150 rpm. The gram-negative bacterium C3 (identified as Pseudomonas parafulva NBRC 16636(T) by 16S rRNA gene sequencing) was able to tolerate cyanide up to 500 ppm besides removing 93.5% of 200 ppm cyanide in 13 days which was confirmed by microorganisms growth. The addition of basal salts enhanced the removal efficiency of C3 by 16%. Cyanide removal efficiency of co-culture was 30% less than C3. Optimization of three significant parameters including temperature, pH, and glucose concentration for cyanide biodegradation was studied using response surface methodology (RSM). The optimum conditions for maximizing cyanide biodegradation were temperature (32.23 °C), pH (9.95), and glucose concentration (0.73 g/l).