Bacterial utilization of cyanide.

Abstract

DURING experiments to determine the fate of potassium cyanide contained in sewage during treatment on percolating filters, a bacterium was isolated capable of growing on silica gel medium containing only potassium cyanide as a source of nitrogen and carbon; traces of iron, copper and phosphate were also present. The organism, which consisted of Gram-positive branching filaments approximately 1µ in diameter, some of which were broken up into bacillary segments, grew on solid medium as a hard, white and powdery colony reaching a maximum of 1 mm. in diameter after incubation for seven days at 28° C. Aerial hyphæ and conidia are present (Fig. 1); but the latter are probably not true reproductive bodies as the organism is killed by drying. The organism is aerobic and a strict autotroph, growth being inhibited in culture by the presence of agar or peptone. It can utilize concentrations of cyanide up to 15 mgm. per 100 ml., but appears to grow best on cyanide concentrations of approximately 4 mgm. per 100 ml. The bacterium was difficult to culture, growth being slow and sparse; but it exhibited surprising activity, a few colonies being able to utilize more than 0.5 mgm. cyanide per day.