The Construction of an Engineered Bacterial Strain and Its Application in Accumulating Mercury from Wastewater

To remove organic and inorganic mercury from wastewater, an engineered bacterial strain, BL21-7, was constructed that contained the artificial operon P16S-g10-merT-merP-merB1-merB2-ppk-rpsT. For BL21-7, the minimum inhibitory concentrations of mercuric chloride, methylmercury chloride and phenylmercury chloride in Luria-Bertani (LB) medium were 100 µmol/L, 60 µmol/L and 80 µmol/L, respectively. After being cultured in three media (liquid LB containing 80 µmol/L mercuric chloride, 40 µmol/L methylmercury chloride or 60 µmol/L phenylmercury chloride) for 72 h, the engineered bacteria accumulated up to 70.5 ± 1.5 µmol/L, 33.5 ± 3.2 µmol/L and 45.3 ± 3.7 µmol/L of mercury, respectively. In the presence of 10 µmol/L Cd2+, 10 µmol/L Pb2+ or 10 µmol/L Cu2+, the accumulation of mercurial derivatives by BL21-7 was not affected. BL21-7 could accumulate mercury well in media with pH values ranging from 5 to 8 and it could work well at temperatures from 25 °C to 37 °C. After BL21-7 was added to wastewater and cultured for 24 h, approximately 43.7% of the Hg in the wastewater was removed.