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

Abstract 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