Effect of Carbon Source and Salinity on Nitrogen Removal of An Aerobic Denitrifier

The aerobic denitrifying bacterium strain LZX301 was analyzed using 16S rDNA sequence. The similarity of 16S DNA sequences between the aerobic denitrifying bacterium strain LZX301 and Pseudomonas stutzeri accessed in GenBank was 99%, and phylogenetic analysis showed that the strain, formed a monophyletic clade with members of P. stutzeri, less closely related to P. aeruginosa or P. putida, which indicated that the strain LZX301 be assigned as the type strain of P. stutzeri. The tests were conducted to study the effect of carbon sources and salinity on the nitrogen removal efficiency when the initial concentrations were 7 mg/L nitrite nitrogen and 28 mg/L nitrate nitrogen in the liquid media with C/N ratio 10, shaking speed at 150 r/min. The inorganic nitrogen removal efficiency was 79.1%、67.9% and 38.8%, and ammonium accumulation was observed to 1.978 mg/L, 1.224 mg/L and 0.727 mg/L for glucose, sodium acetate and sucrose, respectively, which revealed glucose was the most efficient carbon source. With glucose as sole carbon source, nitrate nitrogen removal efficiency was 89.8%、86.1% and 76.5%，nitrite nitrogen removal efficiency was 36.2%, 94.7% and 96.4%, and the accumulated ammonium nitrogen was at 2.117 mg/L, 0.691 mg/L and 0.595 mg/L at salinities of 5 , 15 and 25 , respectively, which revealed the strain LZX301 had good ability in removing inorganic nitrogen at salinities of 5 - 25 . These results implied great potential of the strain LZX301 in practical applications.