Autotrophic denitrification with anaerobic Fe2+ oxidation by a novel Pseudomonas sp. W1

In the present study, a novel Pseudomonas sp. W1 was characterized in terms of its ability to perform nitrate removal coupled with anaerobic Fe2+ oxidation under autotrophic growth condition. The effects of operating parameters with respect to the initial solution pH, temperature and initial Fe2+ concentration on nitrate removal were investigated by central composite design. Based on the results of response surface methodology, the maximal nitrate removal efficiency was achieved under the following conditions: pH 7.0, temperature 30 °C and initial Fe2+ concentration 1,100 mg L−1. Under this optimal condition and with an initial NO3−-N concentration of 55 mg L−1, this strain could remove NO3−-N with 90% reduction of NO3−-N, corresponding to oxidizing Fe2+ with 71% oxidation of Fe2+ after 7 days of incubation. The result of kinetic evaluation indicated that this bacterium showed significant substrate affinity to both NO3−-N and Fe2+.