The small unicellular diazotrophic symbiont, UCYN-A, is a key player in the marine nitrogen cycle.

Martínez-Pérez C, Mohr W, Löscher C R, Dekaezemacker J, Littmann S, Yilmaz P, Lehnen N, Fuchs B M, Lavik G, Schmitz R A, LaRoche J, Kuypers M M (2016); Nat Microbiol., 1(11):16163. doi: 10.1038/nmicrobiol.2016.163