低温反硝化菌——施氏假单胞菌N3的筛选及脱氮性能

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

通过微生物连续富集分离,筛选得到1株低温下具有反硝化能力的细菌N3,鉴定为施氏假单胞菌,并对其脱氮性能进行研究.结果表明,N3在C/N=8,硝酸盐负荷为70 mg·L^(-1)时,能实现硝酸盐的完全去除.此外,N3对低温具有良好的适应性.在C/N=8,4℃条件下,36 h内即可将15 mg·L^(-1)硝酸盐完全去除;反硝化基因nar G和nir S的表达与30℃下的表达量处于同一个数量级,能够高效表达.利用聚乙烯醇(polyvinyl alcohol,PVA)和海藻酸钠(sodium alginate,SA)对N3进行固定化,在10℃下考察固定化N3长期运行的稳定性.结果表明,固定化N3能够在3 d内将15 mg·L^(-1)的硝酸盐完全去除,且连续运行54 d后仍保持良好的稳定性和去除效果.菌株N3具有的高效反硝化脱氮及低温适应性表明其在冬季硝酸盐水体脱氮方面具有良好的应用潜力.

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 ＇ 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.