Characteristics and applications of a heterotrophic nitrifying-aerobic denitrifying bacterium isolated from an urban river

Abstract

A heterotrophic nitrifying-aerobic denitrifying bacterium named "YX3" was newly isolated from an urban river, which had been heavily polluted by domestic sewage and industrial wastewater. Based on similarity of PCR-16S rDNA using universal primers it was identified as Pseudomonas sp. The strain YX3 was found to exhibit excellent abilities with respect to heterotrophic nitrification and aerobic denitrification. Shaking culture experiments were conducted to further investigate the heterotrophic nitrification capacity of this strain. Results showed that optimal conditions for ammonium (NH4+-N) removal were as follows: sodium succinate as carbon source, NH4+-N concentration of 50 mg/L, carbon to nitrogen mass ratio of 15, and pH of 7.0. During a seven-day aerobic denitrification process, the removal rates of nitrate (NO 3--N) and total oxidized nitrogen (NOx--N) achieved 56.26% and 53.99%, respectively. The strain YX3 was later inoculated into river water collected from five sites of the river to determine the removal efficiencies of nitrogen and other compounds from such waters. Results indicated that the highest removal rates of chemical oxygen demand (COD), total nitrogen (TN) and NH4+-N were 61.36%, 50.29% and 57.14%, respectively. Thus, the strain YX3 displayed a high potential for in situ nitrogen removal from eutrophic surface waters. © by psp.