好/厌氧条件下反硝化细菌脱氮特性与功能基因

从西安市金盆水库沉积物中分离筛选出1株高效反硝化细菌,经形态学观察和16S r DNA测序鉴定为施氏假单胞菌(Pseudomonas stutzeri),命名为KK99.探究了该菌株在好/厌氧条件下的脱氮特性以及nar G、nir S和nos Z功能基因的表达水平.结果表明,KK99菌株在好/厌氧条件下,均能进行反硝化作用,且在两种不同的条件下均具有高效的脱氮效率.经过24h的培养,其总氮(TN)去除率分别为85.08%和89.05%.胞内功能基因nos Z和nir S的表达量较高,nos Z在好氧条件下的反硝化发挥主要作用,nir S在厌氧条件下的反硝化发挥主要作用,nar G在两种条件下的表达均较低.同时该菌株还具有同步硝化反硝化性能,在好氧条件下,能同时去除硝酸盐氮和氨氮,24 h时,TN去除率为76%.施氏假单胞菌(P.stutzeri KK99)将为微污染水体富营养化控制和总氮削减工程应用提供菌源保障.

Denitrification Characteristics and Functional Genes of Denitrifying Bacteria Under Aerobic or Anaerobic Conditions

An efficient aerobic denitrifying bacterium was isolated from the sediments of the Jin Pen Reservoir in Xi''an. The strain was identified by morphological features and 16S rDNA sequences as Pseudomonas stutzeri and named it KK99. The denitrification characteristics of the strain and the expression level of the functional genes narG, nirS, and nosZ in aerobic/anaerobic conditions were investigated. The results showed that the strain can carry out both anaerobic and aerobic denitrification and has a high efficiency of denitrification, which occurs under both aerobic and anaerobic conditions; after 24 h, the removal rates of total nitrogen (TN) were 85.08% and 89.05%, respectively. Under both the conditions, the expression levels of the functional genes nosZ and nirS are high. nosZ plays a vital role in denitrification in the aerobic pathway, nirS plays a vital role in denitrification in the anaerobic pathway, and narG expression is low under both the conditions. At the same time, simultaneous nitrification and denitrification (SND) capacity of the strain was observed when nitrate and ammonium salts were the nitrogen sources, with the total nitrogen removal rate being 76% within 24 h in aerobic conditions. The P. stutzeri KK99 strain can be used for controlling eutrophication of micro-polluted water, and the application of total nitrogen reduction engineering.