In a discovery that further demonstrates just how unexpected and unusual nature can be, scientists have found two strains of bacteria whose symbiotic relationship is unlike anything seen before.
Long, thin, hairlike Thioploca (meaning "sulfur braids" in Spanish) trichomes form chains down into marine sediment, which tiny Anammox cells ride down like an elevator. At the bottom, the Anammox cells consume nitrite and ammonium, or "fixed" nitrogen, the waste products of the Thioploca.
The research was conducted off the coast of Baja California, in the anoxic sediments of the Soledad basin at the Mexican Pacific margin. There, bacteria species like Thioploca and Anammox must solve critical challenges.
Nitrogen is a crucial building block of life, a prerequisite for photosynthesis. While nitrogen is present in abundance in the Earth's atmosphere, to be useful for most living organisms, the nonreactive atmospheric di-nitrogen gas that diffuses into the ocean from the air must be converted into the biologically available "fixed" forms ammonium, nitrate and nitrite by specialized organisms called nitrogen fixers. Other organisms use up this fixed nitrogen and convert it back to di-nitrogen gas. Living together in the mud beneath areas of high plant productivity, Thioploca and Anammox intensify this part of the nitrogen cycle.
"There is a growing body of evidence that oceans will be become less oxygenated due to global warming," says Prokopenko. [The thioploca-anammox partnership] occurs in the absence of O2, therefore, it is likely to become more important in the future. But at the same time, it provides a way to put "breaks" on algal growth by enabling anoxic sediments to remove biologically available nitrogen more efficiently than previously thought. Algal growth ultimately drives anoxia (consumes O2). By reducing the amount of fixed nitrogen, the thioploca/anammox consortium ultimately helps the ocean to stay more oxygenated."