Abstract
In this study, 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. Additionally, N. marina is able to grow chemoorganotrophically on formate, and is thus not an obligate chemolithoautotroph. We further investigated the metabolic response of N. marina to low (5.6 µM) O2 concentrations. In response to O2-limited conditions, the abundance of a potentially more efficient CO2-fixing pyruvate:ferredoxin oxidoreductase (POR) complex and a high-affinity cbb3-type terminal oxidase increased, suggesting a role in sustaining nitrite oxidation-driven autotrophy under O2 limitation.
