Characterization of Aerobic Denitrifying Bacterium <em>Pseudomonas mendocina</em> Strain GL6 and Its Potential Application in Wastewater Treatment Plant Effluent

• Main Authors: Wen Zhang, Cheng Yan, Jianing Shen, Ruping Wei, Yan Gao, Aijun Miao, Lin Xiao, Liuyan Yang
• Format: Article
• Language: English
• Published: MDPI AG 2019-01-01
• Series: International Journal of Environmental Research and Public Health
• Subjects: aerobic denitrification; <i>Pseudomonas mendocina</i>; nitrogen removal; response surface methodology; wastewater treatment plant effluent
• Online Access: https://www.mdpi.com/1660-4601/16/3/364

To remove nitrate in wastewater treatment plant effluent, an aerobic denitrifier was newly isolated from the surface flow constructed wetland and identified as <i>Pseudomonas mendocina</i> strain GL6. It exhibited efficient aerobic denitrification ability, with the nitrate removal rate of 6.61 mg (N)·L⁻¹·h⁻¹. Sequence amplification indicated that the denitrification genes <i>napA</i>, <i>nirK</i>, <i>norB</i>, and <i>nosZ</i> were present in strain GL6. Nitrogen balance analysis revealed that approximately 74.5% of the initial nitrogen was removed as gas products. In addition, the response surface methodology experiments showed that the maximum removal of total nitrogen occurred at pH 7.76, C/N ratio of 11.2, temperature of 27.8 °C, and with shaking at 133 rpm. Furthermore, under the optimized cultivation condition, strain GL6 was added into wastewater treatment plant effluent and the removal rates of nitrate nitrogen and total nitrogen reached 95.6% and 73.6%, respectively. Thus, <i>P. mendocina</i> strain GL6 has high denitrification potential for deep improvement of effluent quality.