Heat-tolerant nitrogen-fixing enzyme from deep-sea microbe could inspire cleaner fertilizer
Researchers have characterized a nitrogenase enzyme from the deep-sea archaeon Methanocaldococcus infernus that remains active above 90°C. The enzyme's unusual structure and reaction state may reflect an ancient mechanism for nitrogen fixation. The work could lead to more sustainable ammonia production.
The nitrogenase from Methanocaldococcus infernus contains a metallocofactor considered the most complex metal-based helper structure known in biology. Unlike familiar nitrogenases that rely on molybdenum, vanadium, or iron alone, this enzyme appears to blend characteristics of all three forms. Researchers suggest this hybrid nature could reflect an ancestral version of the enzyme, potentially revealing shared principles underlying all nitrogen fixation reactions.
The enzyme's thermal tolerance proved essential to the investigation. Because the protein remained stable at extreme temperatures, scientists could capture reaction states normally difficult to observe. The microbe was successfully cultivated in the laboratory, allowing the enzyme to be isolated directly and studied at near-atomic resolution through a combination of microbial physiology, purification techniques, and biochemical analysis.
Understanding this heat-stable nitrogenase could eventually inform the design of industrial catalysts for ammonia production, which currently relies on energy-intensive processes. If researchers can replicate the enzyme's mechanism in engineered systems, fertilizer manufacturing may become more sustainable and less dependent on fossil fuels. Agricultural industries and environmental regulators could benefit from cleaner production methods, though practical applications remain years away. The findings also deepen fundamental knowledge of how life evolved to perform one of Earth's most essential chemical transformations.