一株高效好氧反硝化细菌的分离与鉴定

采用选择性培养基通过定量增加亚硝酸盐含量来富集筛选好氧反硝化细菌,经过选择性培养基初步筛选,测定NO-2-N与NO-3-N的去除率,再通过反硝化培养基复筛选出同时具有去除NO-2-N与NO-3-N能力的目的菌。通过16S rRNA基因序列分析及同源性比对以及与其他已筛选出的部分硝化细菌与反硝化细菌的比对构建系统发育树,结合菌株的生理生化鉴定试验,鉴定出目的菌株。在好氧、28℃培养条件下,在反硝化培养基中,该菌株5 d内将NO-2-N由3 570 mg/L降至22 mg/L,去除率达99.4%,将与NO-3-N由2 464 mg/L降至27 mg/L,去除率达98.9%。通过形态学、生理生化反应以及16S rRNA序列测定鉴定菌株DB-6为阴沟肠杆菌(Enterobacter cloacae),命名为DB-6。新筛选的阴沟肠杆菌反硝化能力较强,具有生物脱氮的应用潜质,有望应用于海水养殖水质净化。

Isolation and identification of an efficient aerobic denitrifier

Isolation and identification of an efficient aerobic denitrifying bacteria strain by using the selective medium to isolate and screen aerobic denitrifying bacteria through the quantitative increase of nitrite content, after a preliminary screening, and then second screening through denitrification performance testing for bacterial isolation. Physiological and biochemical tests and 16S rRNA gene amplification and blasting in GenBank ,and phylogenetic tree construction were used to identify the selected strain. Only the DB-6 with effective denitrification .During 5 days, NO₂^- -N was decreased from 3 570 mg/L to 22 mg/L, the removal efficiency was 99.4%, NO₃^- -N was decreased from 2 464 mg/L to 27 mg/L, the removal efficiency was 98.9% and without nitrite accumulation. The strain was identified as Enterobacter cloacae DB-6 according to its morphological, physiological and biochemical characters. In order to further confirm the result, 1 445 bp sequence of DB-6 16S rRNA was amplified and blasted in GenBank. Homology analysis study showed that DB-6 has the highest similarity to Enterobacter cloacae with 99% identity. And phylogenetic tree was constructed together with the discovered nitrifying bacteria, denitrifying bacteria and Enterobacter cloacae. It was suggested that Enterobacter cloacae DB-6 be a novel strain of aerobic denitrifying bacteria,which will be helpful in nitrogen removal of mariculture water.