The primary producers of oxygen on Earth are plants, algae, and cyanobacteria through a process called photosynthesis. There are a few microorganisms that can produce oxygen without sunlight, but they have only ever been found in very small numbers and in very particular settings. The constant presence of oxygen supports plants, algae, and other bacterial life on Earth. Sunlight continues to be essential to photosynthesis. The Earth’s oceans are home to countless species, yet those that can produce oxygen and survive in low light are frequently only found in small numbers. In order to remove bio-available nitrogen from the environment, it was observed that Nitrosopumilus maritimus links the creation of oxygen with the generation of gaseous nitrogen (Shafiee et al., 2022). The bacteria produced enough oxygen to keep the creatures alive in gloomy conditions; however, not enough to have a significant impact on the amounts of oxygen on Earth as a whole.
A marine ammonia-oxidizing archaeon with a strong affinity for ammonia is called Nitrosopumilus maritimus. It fixes carbon using a modified version of the hydroxypropionate/hydroxybutyrate cycle and uses cyanate as a minor source of additional energy and nitrogen (Kraft & Canfield, 2022). Nitrosopumilus maritimus creates its own oxygen when there is a shortage, which could account for why it is frequently seen in anoxic conditions. It is yet unknown which enzymes are involved in the generation of oxygen and the oxidation of ammonia. It was discovered that Nitrosopumilus maritimus could produce oxygen in a dim environment. Not much—certainly not enough to have an impact on Earth’s oxygen levels—but just enough to maintain itself. Although scientists were already aware of the ammonia-oxidizing archaea’s role in maintaining the global nitrogen cycle, they were not fully aware of their capabilities (Evans et al., 2018). Nitrosopumilus maritimus links the synthesis of oxygen and gaseous nitrogen in the recently identified route. They do this by removing nitrogen that is bioavailable from the environment.
References
Evans, T. W., Könneke, M., Lipp, J. S., Adhikari, R. R., Taubner, H., Elvert, M., & Hinrichs, K. U. (2018). Lipid biosynthesis of Nitrosopumilus maritimus dissected by lipid specific radioisotope probing (lipid-RIP) under contrasting ammonium supply. Geochimica et Cosmochimica Acta, 242, 51-63.
Kraft, B., & Canfield, D. E. (2022). Microbe Profile: Nitrosopumilus maritimus. Microbiology, 168(7), 001207.
Shafiee, R. T., Snow, J. T., Hester, S., Zhang, Q., & Rickaby, R. E. (2022). Proteomic response of the marine ammonia‐oxidising archaeon Nitrosopumilus maritimus to iron limitation reveals strategies to compensate for nutrient scarcity. Environmental Microbiology, 24(2), 835-849.