好氧异养硝化菌Acinetobacter sp. YY-5的分离鉴定及脱氮机理

Isolation and Denitrification Mechanism of an Aerobic Heterotrophic Bacterium Acinetobacter sp. YY-5

通过异养硝化培养基获得一株高效脱氮细菌,并通过形态学特征、生理生化反应及16S rDNA同源性比较对筛得菌株进行了鉴定;分别以NO3--N和NO2--N为唯一氮源,通过对脱氮过程中各种含氮代谢物的定量及对脱氮相关基因氨单加氧酶基因(amoA)、羟胺氧化酶基因(hao)、周质硝酸盐还原酶亚基基因(napA)的扩增及测序比较,对该菌株的生理途径及脱氮机理进行了研究.结果表明,高效脱氮细菌YY-5不能发生好氧反硝化,但能在3d内将氨氮由95.23mg/L降解至1.29mg/L,降解率达到98.6%,同时未发现亚硝酸盐氮、硝酸盐氮积累;对该菌主要代谢气体产物进行检测,发现CO2和N2明显增多,无N2O生成;经鉴定,初步判定该菌为不动杆菌属,命名为Acinetobacter sp. YY-5;从该菌基因组中均能扩增出amoA、hao、napA等基因,其中napA与hao基因与已报道的napA与hao基因进行Blast比较,发现具有较大差别.

An aerobic heterotrophic bacterium YY-5, which could degrade NH4^＋ -N from 95.23 mg/L to 1.29 mg/L in 3 days, was studied to reveal its denitrification methanism at the level of product characteristics and several denitrification enzymes encoding genes. The results demonstrated the bacteria produced large quantities of CO2 and N2, but small nitrite and nitrate accumulations. Furthermore, strain YY-5 had ammonia monooxygenase encoding gene （arnoA） which encodes the enzyme to oxidize ammonia to hydroxylamine. Also, the strain had a new hydroxylamine oxidoreductase encoding gene （hao） whose sequence was distinct not only to that of autotrophic bacteria but also to that of heterotrophic bacteria. Its napA gene was also great different with the reported genes from the known aerobic heterotrophic bacteria by Blast comparison. The strain was identified as Acinetobacter sp. YY-5 according to its morphological, physiological and biochemical characters, as well as 16S rDNA sequence homology comparison. Fig 6, Tab 3, Ref 15