| Abstrak/Abstract |
Small-scale gold mining activities in Cineam, Tasikmalaya, West Java Province, Indonesia still use amalgamation techniques, which have the potential to cause mercury (Hg) pollution and have an impact on the quality and number of microorganisms, especially heterotrophic bacteria. Mercury-resistant bacteria are able to survive and adapt to mercury-exposed environments and can be developed as bioremediation agents. The bioremediation activity of these bacteria can be increased through immobilization using biochar. The results of observations of physicochemical qualities including total organic carbon (TOC) and pH in the 3 samples in the mining area showed significant differences. TOC in the soil rhizosphere sample of Caliandra callothyrursus L showed the highest value significantly at 14.5%, while the pH values of the three samples tended to be acidic and showed no difference (p<0.05). The highest Hg concentration measured in the tailings sample was 9.9 ng/g (p<0.05). The number of heterotrophic bacteria in the soil rhizosphere showed the highest result of 7.2 × 108 CFU/g, on the other hand, the number of mercury-resistant bacteria in the tailings sample showed the highest value of 6.3 × 103 CFU/g. In the selection based on the toxicity profile of 30 mercury resistant bacteria obtained, the highest results were observed in the LMP1B5 bacterial isolate isolated from river sediment with EC50 and MIC values of 225 mg/L and 250 mg/L, respectively. Polyphasic identification based on phenotypic and genotypic characters using the 16S rRNA gene showed that the bacterial isolate was identified as Escherichia fergusonii. The growth and mercury removal activity of E. fergusonii LMP1B5 increased by 21% and 52%, respectively, after immobilization with biochar. Thus, E. fergusonii LMP1B5 immobilized was effective in removing mercury pollutant. The results of this treatment have the potential to develop bioremediation technology that is able to clean the environment from mercury pollution. |
