Isolation and characterization of strain for Fe(III)Cit reduction

A strain which can reduce Fe(III)Cit (Cit: citrate) efficiently was isolated from the mixed culture of chemical absorption-biological reduction integrated system. Through molecular biological identification, the strain belongs to enterococcus, and was named to be Enterococcus sp. FR-3. The effects of carbon source species, nitrogen source species, the inoculation amount of cells and pH-value on the strain FR-3 growth and its Fe(III)Cit reduction ability were investigated respectively. The results demonstrate that the glucose is the most suitable carbon source for the strain FR-3 growth and Fe(III)Cit reduction, and the optimal glucose adding amount is 1000 mg·mL-1. When using NH4Cl as nitrogen source, FR-3 growth and Fe(III)Cit reduction efficiency are better than that of using NaNO2, and the optimal NH4Cl adding amount is 100 mg·mL-1. The bio-reduction of Fe(III)Cit can be achieved efficiently with the cells inoculation amount of 150 mg·mL-1, and the reduction rate would not further increase with adding more amount of cells inoculation. The optimal pH range found for Fe(III)Cit reduction is 6.6~7.0.