Nitric oxide (NO) is a central molecule in the global cycling of nitrogen, and also toxic. Little is known about if and how microbes can use NO as a substrate for growth. Scientists from the Max Planck Institute for Marine Microbiology in Bremen, Germany, have now managed to grow a microbial community dominated by two, so-far unknown species on NO for more than four years (and counting) and study their metabolism in great detail. Their research, now published in in Nature Microbiology, provides insight into the physiology of NO-reducing microorganisms, which have pivotal roles in the control of climate active gases, waste removal, and the evolution of nitrate and oxygen respiration.