Ecophysiology of the cosmopolitan nitrite-oxidising genus Candidatus Nitromaricola.

Candidatus Nitromaricola pontica is a globally abundant marine nitrite-oxidising bacterium capable of oxidising nitrite in both oxic and anoxic waters, with higher abundance in oxygenated zones.

• Why it matters: Understanding the ecophysiology of key nitrate-producing microorganisms like Ca. Nitromaricola is crucial for comprehending nitrogen cycling in the ocean, yet their roles remain poorly characterized.
• What they did: Researchers characterized Ca. Nitromaricola in the Black Sea, analyzing its environmental distribution, genomic features, and nitrogen sources through in situ studies and single-cell analyses across environmental gradients.
• The result: The study reveals that Ca. Nitromaricola actively oxidizes nitrite and fixes inorganic carbon without canonical high affinity terminal oxidases, mainly utilizing ammonium and urea for biomass, underscoring its widespread ecological significance.