好氧反硝化菌Defluvibacter lusatiensis str. DN7的分离鉴定和异养硝化性能

从稳定运行处理竹子加工废水的生物接触氧化反应器中分离得到一株好氧反硝化菌DN7,其72 h NO₃^-降解率达99.4%.细胞显微镜观察显示,菌株为革兰氏阴性小杆菌,大小为0.5 μm×1.5 μm,菌落为乳白色.通过生理生化特性及16S rDNA同源性分析,初步推断该菌株为根瘤菌中的Defluvibacter lusatiensisstr.碳源、C/N、硝酸盐初始浓度、溶解氧(DO)、pH对DN7反硝化性能影响的结果表明:菌株对柠檬酸钠、葡萄糖等小分子有机物的利用较好;C/N为9时,脱氮率达99.0%;硝酸盐浓度低于138.48 mg·L^-1情况下,DN7脱氮率在96%以上,且亚硝酸盐浓度均在1.0 mg·L^-1以下;菌株DN7对DO不敏感,中性偏碱性环境有利于DN7反硝化反应的进行;DN7具有良好的异养硝化性能,72 h铵氮降解率达84.7%.

Isolation and identification of aerobic denitrifying bacterium Defluvibacter lusatiensis strain DN7 and its heterotrophic nitrification ability.

An aerobic denitrifying bacterium strain DN7 with excellent nitrate removal ability was isolated from the bio contact oxidation reactor treating bamboo process wastewater. The strain had a nitrate removal efficiency of 99.4% in 72 h. Cell microscopic observation demonstrated that the strain was a gram negative bacillus with an average size of 0.5 μm×1.5 μm, and the colony was ivory. Based on its biochemical/morphological characteristics and its 16S rDNA sequence homologic analysis, this strain was identified as Defluvibacter lusatiensis. Its optimal carbon sources were small molecular organic compounds such as sodium citrate and glucose, and its nitrogen removal efficiency reached 99.0% when the medium C/N ratio was 9. The nitrogen removal efficiency could reach more than 96% when the nitrate concentration was below 138.48 mg·L-1 and the nitrite concentration was lower than 1.0 mg·L-1. The strain was not sensitive to DO, and the denitrification was favored under neutral or a bit alkaline condition. The DN7 also had good ability in degrading ammonim nitrogen, with the removal efficiency being 84.7% in 72 h.