Acinetobacter baumannii is an opportunistic human pathogen that has become a global threat to healthcare institutions worldwide. The success of A. baumannii is based on the rise of multiple antibiotic resistances and its outstanding potential to persist in the human host and under conditions of low water activity in hospital environments. Combating low water activities involves osmoprotective measures such as uptake of compatible solutes and K⁺. To address the role of K⁺ uptake in the physiology of A. baumannii we have identified K⁺ transporter encoding genes in the genome of A. baumannii ATCC 19606. The corresponding genes (kup, trk, kdp) were deleted and the phenotype of the mutants was studied. The triple mutant was defective in K⁺ uptake which resulted in a pronounced growth defect at high osmolarities (300 mM NaCl). Additionally, mannitol and glutamate synthesis were strongly reduced in the mutant. To mimic host conditions and to study its role as an uropathogen, we performed growth studies with the K⁺ transporter deletion mutants in human urine. Both, the double (ΔkupΔtrk) and the triple mutant were significantly impaired in growth. This could be explained by the inability of ΔkupΔtrkΔkdp to metabolize various amino acids properly. Moreover, the reactive oxygen species resistance of the triple mutant was significantly reduced in comparison to the wild type, making it susceptible to one essential part of the innate immune response. Finally, the triple and the double mutant were strongly impaired in Galleria mellonella killing giving first insights in the importance of K⁺ uptake in virulence.

鲍曼不动杆菌是一种机会主义的人类病原体，已成为全球医疗保健机构的全球威胁。A. baumannii的成功基于多重抗生素耐药性的出现及其在人类宿主中和在医院环境中的低水分活度条件下持续存在的突出潜力。对抗低水活性涉及渗透保护措施，例如吸收相容溶质和 K ⁺。为了解决K的作用⁺中的生理摄取鲍曼不动杆菌，我们已经确定ķ ⁺编码的基因组中基因转运鲍曼不动杆菌ATCC 19606.相应的基因（KUP，trk , kdp ) 被删除并研究了突变体的表型。三重突变体在 K ⁺吸收方面存在缺陷，导致在高渗透压（300 mM NaCl）下出现明显的生长缺陷。此外，甘露醇和谷氨酸的合成在突变体中大大减少。为了模拟宿主条件并研究其作为泌尿病原体的作用，我们对人类尿液中的 K ⁺转运蛋白缺失突变体进行了生长研究。双突变体（Δ kup Δ trk）和三重突变体的生长均显着受损。这可能是由于无法Δ来解释KUP Δ TRK Δ KDP适当地代谢各种氨基酸。此外，与野生型相比，三重突变体的活性氧抗性显着降低，使其易受先天免疫反应的一个重要部分的影响。最后，三重和双突变体在大蜡螟的杀死中受到严重损害，从而首次了解了 K ⁺吸收在毒力中的重要性。