Appl Environ Microbiol. 1997 Nov;63(11):4588-92. doi: 10.1128/aem.63.11.4588-4592.1997.
The obligately ammonia-oxidizing bacterium Nitrosomonas europaea was incubated in medium containing 50 mM ammonium. Changes in the concentration of nitrite, the pH, and the NH(inf4)(sup+)- and NH(inf2)OH-dependent O(inf2) uptake activities of the cell suspension were monitored. The NH(inf4)(sup+)-dependent O(inf2) uptake activity doubled over the first 3 h of incubation and then slowly returned to its original level over the following 5 h. The extent of stimulation of NH(inf4)(sup+)-dependent O(inf2) uptake activity was decreased by lowering the initial pH of the medium. Radiolabeling studies demonstrated that the stimulation of NH(inf4)(sup+)-dependent O(inf2) uptake activity involved de novo synthesis of several polypeptides. Under O(inf2)-limited conditions, the stimulated NH(inf4)(sup+)-dependent O(inf2) uptake activity was stabilized. Rapid, controlled, and predictable changes in this activity could be caused by acidification of the medium in the absence of ammonia oxidation. These results indicate that the NH(inf4)(sup+)-dependent O(inf2) uptake activity in N. europaea is strongly regulated in response to NH(inf3) concentration.
严格依赖氨的细菌硝化单胞菌（Nitrosomonas europaea）在含有 50mM 氨的培养基中培养。监测细胞悬浮液中亚硝酸盐浓度、pH 值以及 NH(inf4)(sup+)-和 NH(inf2)OH 依赖的 O(inf2)摄取活性的变化。在孵育的最初 3 小时内，NH(inf4)(sup+)-依赖的 O(inf2)摄取活性增加了一倍，然后在接下来的 5 小时内缓慢恢复到原来的水平。降低培养基的初始 pH 值会降低 NH(inf4)(sup+)-依赖的 O(inf2)摄取活性的刺激程度。放射性标记研究表明，NH(inf4)(sup+)-依赖的 O(inf2)摄取活性的刺激涉及几种多肽的从头合成。在 O(inf2)有限的条件下，刺激的 NH(inf4)(sup+)-依赖的 O(inf2)摄取活性得到稳定。在没有氨氧化的情况下，通过酸化培养基可以快速、可控和可预测地改变这种活性。这些结果表明，硝化单胞菌（N. europaea）中 NH(inf4)(sup+)-依赖的 O(inf2)摄取活性强烈响应 NH(inf3)浓度进行调节。
