New insight into the nitrogen metabolism of simultaneous heterotrophic nitrification-aerobic denitrification bacterium in mRNA expression
New insight into the nitrogen metabolism of simultaneous heterotrophic nitrification-aerobic denitrification bacterium in mRNA expression
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同步异养硝化-好氧反硝化细菌氮代谢mRNA表达的新见解
DOI：
10.1016/j.jhazmat.2019.03.023
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发表时间：
2019-06-05
影响因子：
13.6
通讯作者：
Du, Qizhen
中科院分区：
文献类型：
--
作者：
Jin, Peng;Chen, Yinyan;Du, Qizhen
在这里，基因组草图同步硝化反硝化菌株（SND）克雷伯氏菌。KSND揭示了可能存在的基因参与N-同化和N-异化途径。采用实时荧光定量PCR技术分析了不同氮源条件下基因表达的变化。这表明NH 4+同化作用优先通过NADP-谷氨酸脱氢酶途径进行。NirBD基因在较低水平上受到严格调控，从而使亚硝酸盐被快速消耗以通过反硝化作用解毒。三种类型的硝酸还原酶同系物是令人惊讶地存在于KSND，而主导的硝酸还原同化和反硝化过程介导的NapA型硝酸还原酶。一氧化氮还原酶同系物FlRd和FlRd-红提供了足够的NO解毒能力。重组羟胺还原酶对羟胺有较高的还原活性，并能产生铵离子，这可能与氮循环中的解毒机制有关。总之，本研究首次提供了有价值的见解基因表达和酶的行动，这有助于了解SND过程的机制。
Here, the draft genome of simultaneous nitrification-denitrification strain (SND) Klebsiella sp. KSND revealed possible existence of genes involved in N-assimilation and -dissimilation pathways. The change levels of genes under defined N-sources were analyzed by Quantitative Real-Time PCR. It suggested that NH4+-assimilation via NADP-glutamate dehydrogenase pathway would occur preferentially. NirBD genes were tightly regulated in a lower level, so that nitrite was rapidly consumed for detoxication by denitrification. Three types of nitrate reductase homologues are surprisingly present in KSND, whereas the dominant nitrate reduction for assimilation and denitrification processes mediates by NapA-type nitrate reductase. Nitric oxide reductase homologues FlRd and FlRd-red provide an adequate capacity for NO detoxification. The recombinant hydroxylamine reductase showed high activity in hydroxylamine to generate ammonium, which might contribute to detoxification mechanism in nitrogen cycling. Overall, this study firstly provides valuable insights into the genes expression and enzyme action, which helps understanding the mechanism of SND processes.