Biological nitrogen fixation in acidic high‐temperature geothermal springs in Yellowstone National Park, Wyoming

Researchers have discovered that biological nitrogen fixation occurs in acidic, high-temperature geothermal springs within Yellowstone National Park, extending the known upper temperature limit for this process in terrestrial systems. The study identified three unique phylotypes of nifH genes in sediment samples from 14 springs (ranging from 48.0°C to 89.0°C and pH 1.90–5.02), which are distantly related to known acidiphilic diazotrophs. Acetylene reduction assays and (15)N(2) tracer studies confirmed active nitrogen fixation, with rates linked to ammonia concentrations. A highly enriched culture revealed a dominant nifH phylotype present across all samples, suggesting significant contributions of fixed nitrogen to these ecosystems.

Hamilton, T. L., Lange, R. K., Boyd, E. S., & Peters, J. W. (2011). Biological nitrogen fixation in acidic high‐temperature geothermal springs in Yellowstone National Park, Wyoming. Environmental Microbiology, 13(8), 2204–2215. Portico. https://doi.org/10.1111/j.1462-2920.2011.02475.x