Indigenous Mercury Resistant Bacterial Isolates Belong To The Genus Bacillus From Kalimas Surabaya As A Potential Mercury Bioreducer

Three potential mercury resistant isolates (11 mg/L HgCl2) belong to the genus Bacillus, namely Bacillus sp. S1, SS19, and DA11 obtained from Kalimas Surabaya were studied. Bacterial isolates were inoculated into nutrient broth containing 10, 15, and 15 mg/L HgCl2, and incubated for 24 h at room temperature. Hg2+ concentration determination was prepared according to standard procedure of US Environmental Protection Agency (EPA) 200.7, and measured by Inductively Coupled Plasma Atomic Emission Spectrometry(ICP). The amount of Hg2+ reduction by the isolates was expressed as percentage of reduction from the original concentration. Results of the study showed that the highest capacity of the isolates to reduce HgCl2 were different, namely, the isolates DA11 and S1 could reduce 74.5% and 63.6% at the original concentration of 10 mg/L, respectively, whrereas the isolate SS19 could only reduce 53.6% at the original concentration of 5 mg/L. Therefore, in terms of the capacity of bioreduction, the indigenous bacterial isolate (DA11) belong to the genus Bacilluscould be used as potential mercury bioreducer.