From several mercury removing microorganisms, we selected Bacillus megaterium MB1, which is non-pathogenic, broad-spectrum mercury resistant, mercuric ion reducing, heat tolerant, and spore-forming, as a useful bacterium for bioremediation of mercury pollution. In this study, mercury removal performance of the immobilized B. megaterium MB1 was investigated to develop safe, efficient and stable catalytic bio-agent for mercury bioremediation. The results showed that the alginate gel immobilized B. megaterium MB1 cells efficiently removed 80% of mercury from the solution containing 10 mg/L mercuric chloride within 24 h. These cells still had high activity of mercury removal even after mercuric ion loading was repeated for nine times. The analysis of mercury contents of the alginate beads with and without immobilized B. megaterium MB1 suggested that a large portion of reduced metallic mercury was trapped in the gel beads. It was concluded that the alginate gel immobilized B. megaterium MB1 cells have potential to remove and recover mercury from mercury-containing water.
Relative mercury volatilization activity in each loading of mercuric ion /% a)
1st
2nd
3rd
4th
5th
6th
7th
8th
9th
ImmobilizedB. megaterium MB1
100.0
116.5(0.1)
91.7(0.1)
84.9(0.2)
111.7(2.3)
103.6(1.2)
64.6(0.5)
70.6(0.4)
79.0(0.8)
Free-livingB. megaterium MB1
100.0
90.2(0.5)
65.4(2.5)
57.3(3.7)
30.1(7.5)
7.5(2.1)
5.1(2.6)
4.3(3.1)
3.7(2.3)
Tab.2
Fig.4
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