The genus Nitrospira is the most widespread group of nitrite-oxidizing bacteria and thrives in diverse natural and engineered ecosystems. Nitrospira marina Nb-295^T was isolated from the ocean over 30 years ago; however, its genome has not yet been analyzed. Here, we investigated the metabolic potential of N. marina based on its complete genome sequence and performed physiological experiments to test genome-derived hypotheses. Our data confirm that N. marina benefits from additions of undefined organic carbon substrates, has adaptations to resist oxidative, osmotic, and UV light-induced stress and low dissolved pCO₂, and requires exogenous vitamin B₁₂. In addition, N. marina is able to grow chemoorganotrophically on formate, and is thus not an obligate chemolithoautotroph. We further investigated the proteomic response of N. marina to low (∼5.6 µM) O₂ concentrations. The abundance of a potentially more efficient CO₂-fixing pyruvate:ferredoxin oxidoreductase (POR) complex and a high-affinity cbb₃-type terminal oxidase increased under O₂ limitation, suggesting a role in sustaining nitrite oxidation-driven autotrophy. This putatively more O₂-sensitive POR complex might be protected from oxidative damage by Cu/Zn-binding superoxide dismutase, which also increased in abundance under low O₂ conditions. Furthermore, the upregulation of proteins involved in alternative energy metabolisms, including Group 3b [NiFe] hydrogenase and formate dehydrogenase, indicate a high metabolic versatility to survive conditions unfavorable for aerobic nitrite oxidation. In summary, the genome and proteome of the first marine Nitrospira isolate identifies adaptations to life in the oxic ocean and provides insights into the metabolic diversity and niche differentiation of NOB in marine environments.

Nitrospira属是分布最广的一类亚硝酸盐氧化细菌，在各种自然和工程生态系统中繁衍生息。Nitrospira marina Nb-295 ^T是在 30 多年前从海洋中分离出来的；然而，它的基因组尚未被分析。在这里，我们根据其完整的基因组序列研究了N. marina的代谢潜力，并进行了生理学实验以检验基因组衍生的假设。我们的数据证实，N. marina受益于添加未定义的有机碳底物，具有抵抗氧化、渗透和紫外线诱导的压力和低溶解p CO ₂的适应性，并且需要外源维生素 B₁₂。此外，N. marina能够在甲酸盐上进行化学有机营养生长，因此不是专性化学自养生物。我们进一步研究了N. marina对低 ( ∼ 5.6 µM) O ₂浓度的蛋白质组学反应。_{在 O 2}限制下，可能更有效地固定 CO ₂的丙酮酸：铁氧还蛋白氧化还原酶 (POR) 复合物和高亲和力cbb ₃型末端氧化酶的丰度增加，表明其在维持亚硝酸盐氧化驱动的自养中的作用。这假定更多的 O ₂- 敏感的 POR 复合物可能受到 Cu/Zn 结合超氧化物歧化酶的氧化损伤保护，在低 O ₂条件下其丰度也会增加。此外，参与替代能量代谢的蛋白质的上调，包括第 3b 组 [NiFe] 氢化酶和甲酸脱氢酶，表明在不利于有氧亚硝酸盐氧化的条件下生存的高代谢多功能性。总之，第一个海洋Nitrospira分离株的基因组和蛋白质组确定了对含氧海洋中生命的适应性，并提供了对海洋环境中 NOB 的代谢多样性和生态位分化的见解。