Isolation of the Hg(II)‐volatilizing Bacillus sp. strain DC‐B2 and its potential to remediate Hg(II)‐contaminated soils

BACKGROUND: Mercury (Hg) contamination is a major global environmental problem, and its remediation using environmentally friendly biotechnologies has attracted increasing attention. In this study, an Hg(II)‐resistant bacterial strain, Bacillus sp. DC‐B2, was isolated from a metal‐contaminated site, and its ability to remediate five types of Hg‐contaminated soils was investigated. RESULTS: The isolate DC‐B2 showed strong resistance to multiple metals and volatilized 91.6% of the Hg(II) in a culture with an initial Hg(II) concentration of 10 mg L⁻¹ within 8 h. Microcosm experiments showed that the addition of DC‐B2 culture improved Hg(II) removal by 11.7–17.2% from four artificially Hg(II)‐spiked soil samples with initial Hg contents of approximately 100 mg kg⁻¹ after incubating for 30 days under flooded conditions compared to the control treatment. For the field‐contaminated farmland soil containing 2.50 mg Hg kg⁻¹, an Hg(II) elimination rate of 82.1% was achieved within 30 days with the DC‐B2 inoculation, relative to the 34.1% elimination rate observed for the uninoculated control. The amendment of peptone broth slightly inhibited Hg removal (2.2–8.7%). The remediation effectiveness was verified by observations of longer root and shoot lengths of lettuce plants grown in treated soils compared to those grown in the control soil. CONCLUSION: The isolate Bacillus sp. DC‐B2 shows great potential to be developed as a bioagent for effective bioremediation of Hg‐contaminated soils. © 2018 Society of Chemical Industry