Isolation and identification of manganese-oxidizing bacteria in groundwater

Three strains of gram-negative bacteria, named Mn1, Mn2 and Mn3, which were capable of effective Mn²⁺ oxidization were identified in the water of water-supply plant in Zhangshi economic development zone, Shenyang, PRC. Phylogenetic analysis showed that strain Mn1 and strain Mn2 may belong to the family of Delftia, while strain Mn3 was in the family of Klebsiella. The capability of Mn²⁺ oxidation and fermentation characteristics of these three bacteria were measured using groundwater containing 2 mg/L Mn²⁺. The results showed that the biomass of those bacteria accumulated through 12 h incubation to a level satisfying the requirement of a 1 m³ biofilter and the relative oxidation of Mn²⁺ were about 96%, 94% and 85%, respectively, for Mn1, Mn2 and Mn3. The strains obtained may be of significance for a rapid initiation of biofilter in underground water treatment.