Hidden fuel for ocean microbes: Urea emerges as key energy source for marine ammonia oxidizers

Ammonia-oxidizing archaea (AOA) are some of the most abundant microorganisms in the ocean and play a key role in nitrogen cycling. Yet, despite their ubiquity, scientists have long puzzled over how these microbes can flourish in the nutrient-poor waters of the open ocean, where their main nitrogen and energy source, ammonium, is often vanishingly scarce.

source https://phys.org/news/2025-12-hidden-fuel-ocean-microbes-urea.html