Application of mercury resistant bacteria isolated from artisanal small-scale gold tailings in biotransformation of mercury (II)-Contaminated soil

Abstract

This research aims to study the detoxification of Hg by a consortium of bacteria throughout bioremediation technology. The consortium of bacteria was identified to be the strain of Bacillus cereus TL-01, Bacillus Sp TL-02 and Brevundimonas diminuta TL-03 by 16s rRNA sequencing. The result presented the potential of growth in the used medium and bacteria grew faster orderly in no/less to high Hg concentration. Bacteria started its log phase after 4 and 20 hours inoculation in pure culture and 50 ppm Hg while the growth prolonged its lag phase to 52 hours in 100 ppm Hg. Experimental treatments were done using synthetic soil under an anaerobic condition with 60 days of observation. For a microcosm of soil treatment, the highest removal of mercury under influence of temperature was 73 % at 45°C while the highest removal under influence of pH was 69% at pH of 4-5 and the highest removal under nutrient amendment was at CNP of 100:10:1 with an efficiency of 75%. There was 0.02% of Hg0 found to be adsorbed onto the activated carbon analyzed by SEM-EDS. The oxidation-reduction potential (ORP) was measured in the range of-60 mv to 80 mv ranging in reduced soil considered into anaerobic condition. To sum up, the isolated bacteria represents to potential in detoxifying Hg while Hg removal was better with the anaerobic condition. A high concentration of Hg did not inhibit the growth of isolated bacteria but it just prolonged the adaptation stage of bacteria.