In the Artvin-Kafkasor ore deposit gold and silver are the main precious me
tals and are associated with quartz and limonite. In the present investigat
ion, a fungal culture isolated from a mine water was tested under laborator
y conditions for its bioleaching potential for enhancing silver recovery pr
ior to cyanidation. The silver recovery was expressed as both the silver di
ssolved after biotreatment and that recovered after cyanidation following b
iotreatment. Silver recovery increased as a function of fungal pretreatment
time. After 40 days, silver recovery was about 83% (of which 15% was due t
o direct microbial action). The recovery by cyanidation alone, on the other
hand (as observed with the uninoculated control), was 53%. These results s
uggest that the microbial action favours a more effective cyanidation by ch
anging the physical properties of the ore.