[Characterization of a Newly Isolated Strain Pseudomonas sp. N3 for Denitrification at Low Temperature]

Based on traditional microbiological methods, a novel denitrifier Pseudomonas sp. N3 with excellent denitrification capacity at low temperature was isolated and identified using phenotypic and phylogenetic analysis. Complete nitrate removal was achieved at C/N=8, that is, 70 mg·L^-1 nitrate. In addition, the isolate exhibited a great adaptability for low temperature and can reach 100% removal of 15 mg·L^-1 nitrate at a temperature as low as 4℃ within 36 h. The denitrification genes of narG and nirS were highly expressed; they were at the same order of magnitude as those at 30℃. Semicontinuous experiments were conducted to test the stability of N3 immobilized with polyvinyl alcohol and sodium alginate at 10℃. The results show that immobilized N3 can remove 15 mg·L^-1 nitrate completely within three days and maintains a strong mechanical performance and stability during the whole 54 days. The cold resistance and high denitrification ability of the strain N3 make it applicable to nitrogen wastewater treatment in winter.