CHARACTERIZATION OF A NITRATE-UPTAKE BACTERIAL STRAIN Bacillus megaterium NCT-2

A novel nitrate-uptake bacterial strain Bacillus megaterium NCT-2 was isolated from greenhouse soil. This isolate could utilize nitrate as sole source of nitrogen. The resting cells could remove nitrate over 200 mg/L within 48h. Although nitrate was not essential for the growth of this microorganism, it increased the growth rate. To characterize the microbial nitrate uptake, we measured the effect of sodium chloride and heavy metal ions on the uptake. The increase of sodium chloride concentration inhibited the nitrate removal. When sodium chloride concentration exceed 10%, only very little uptake was observed. And that inhibitory effect of sodium chloride on both nitrate uptake and bacterial growth was dose-dependent. The heavy metal ions, such as Ni2+, Cd2+, and Cu2+, could inhibit the nitrate uptake. In the opposite case, Zn2+ and Mn2+ had no effects on the nitrate removal. Furthermore, Fe(3+)can significantly promote the uptake. The effects of metal ions on uptake were consistent with that on the growth of strain NCT-2. This study suggested the strain NCT-2 could be widely used for bioremediation of soil contaminated by nitrate.