Metabolically-versatile Ca. Thiodiazotropha symbionts of the deep-sea lucinid clam have the genetic potential to fix nitrogen.

Lucinid clams are one of the most diverse and widespread symbiont-bearing animal groups in both shallow and deep-sea chemosynthetic habitats. Lucinids harbor Ca. Thiodiazotropha symbionts that can oxidize inorganic and organic substrates such as hydrogen sulfide and formate to gain energy.