Through our previous study, we found an up-regulation in the expression of nitrite reductase (nirS) in the isothiazolone-resistant strain of Pseudomonas aeruginosa. However, the definitive molecular role of nirS in ascribing the resistance remained elusive. In the present study, the nirS gene was deleted from the chromosome of P. aeruginosa ATCC 9027 and the resulting phenotypic changes of ΔnirS were studied alongside the wild-type (WT) strain under aerobic conditions. The results demonstrated a decline in the formations of biofilms but not planktonic growth by ΔnirS as compared to WT, especially in the presence of benzisothiazolinone (BIT). Meanwhile, the deletion of nirS impaired swimming motility of P. aeruginosa under the stress of BIT. To assess the influence of nirS on the transcriptome of P. aeruginosa, RNA-seq experiments comparing the ΔnirS with WT were also performed. A total of 694 genes were found to be differentially expressed in ΔnirS, of which 192 were up-regulated, while 502 were down-regulated. In addition, these differently expressed genes were noted to significantly enrich the carbon metabolism along with glyoxylate and dicarboxylate metabolisms. Meanwhile, results from RT-PCR suggested the contribution of mexEF-oprN to the development of BIT resistance by ΔnirS. Further, c-di-GMP was less in ΔnirS than in WT, as revealed by HPLC. Taken together, our results confirm that nirS of P. aeruginosa ATCC 9027 plays a role in BIT resistance along with biofilm formation and further affects several metabolic patterns under aerobic conditions.

中文翻译：

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nirS在有氧条件下在铜绿假单胞菌ATCC 9027中的生物学功能。

通过我们先前的研究，我们发现铜绿假单胞菌的异噻唑酮抗性菌株中亚硝酸还原酶（nirS）表达的上调。但是，nirS在确定抗性方面的确定性分子作用仍然难以捉摸。在本研究中，从铜绿假单胞菌ATCC 9027的染色体上删除了nirS基因，并在有氧条件下与野生型（WT）菌株一起研究了ΔnirS的表型变化。结果表明，与WT相比，ΔnirS减少了生物膜的形成，但没有浮游生物的生长，特别是在存在苯并异噻唑啉酮（BIT）的情况下。同时，在BIT的压力下，缺失nirS会损害铜绿假单胞菌的游泳运动。为了评估nirS对铜绿假单胞菌转录组的影响，还进行了将ΔnirS与WT进行比较的RNA-seq实验。发现总共694个基因在ΔnirS中差异表达，其中192个上调，而502个下调。另外，注意到这些不同表达的基因与乙醛酸和二羧酸酯代谢一起显着丰富了碳代谢。同时，RT-PCR的结果表明mexEF-oprN对ΔnirS对BIT抗性发展的贡献。此外，如HPLC所示，ΔnirS中的c-di-GMP小于WT中的c-di-GMP。两者合计，我们的结果证实，铜绿假单胞菌ATCC 9027的nirS在BIT抵抗以及生物膜形成中起作用，并进一步影响有氧条件下的几种代谢模式。其中192个上调，而502个下调。另外，注意到这些不同表达的基因与乙醛酸和二羧酸酯代谢一起显着丰富了碳代谢。同时，RT-PCR的结果表明mexEF-oprN对ΔnirS对BIT抗性发展的贡献。此外，如HPLC所示，ΔnirS中的c-di-GMP小于WT中的c-di-GMP。两者合计，我们的结果证实，铜绿假单胞菌ATCC 9027的nirS在BIT抵抗以及生物膜形成中起作用，并进一步影响有氧条件下的几种代谢模式。其中192个上调，而502个下调。另外，注意到这些不同表达的基因与乙醛酸和二羧酸酯代谢一起显着丰富了碳代谢。同时，RT-PCR的结果表明mexEF-oprN对ΔnirS对BIT抗性发展的贡献。此外，如HPLC所示，ΔnirS中的c-di-GMP比WT中的少。两者合计，我们的结果证实，铜绿假单胞菌ATCC 9027的nirS在BIT抵抗以及生物膜形成中起作用，并进一步影响有氧条件下的几种代谢模式。RT-PCR的结果表明mexEF-oprN对ΔnirS对BIT抗性发展的贡献。此外，如HPLC所示，ΔnirS中的c-di-GMP小于WT中的c-di-GMP。两者合计，我们的结果证实，铜绿假单胞菌ATCC 9027的nirS在BIT抵抗以及生物膜形成中起作用，并进一步影响有氧条件下的几种代谢模式。RT-PCR的结果表明mexEF-oprN对ΔnirS对BIT抗性发展的贡献。此外，如HPLC所示，ΔnirS中的c-di-GMP比WT中的少。两者合计，我们的结果证实铜绿假单胞菌ATCC 9027的nirS在BIT抵抗以及生物膜形成中起作用，并进一步影响有氧条件下的几种代谢模式。