Isolate bacteria that oxidize self-sustaining ammonia in the sea

For many years, microbiologists believe that ancient bacteria are ' extremophile ' (living organisms in extremely harsh environments). The limited physiological diversity of cultured bacteria indicates that they are forced to metabolize in some environmental drives. For example, all species currently cultivated in Crenarchaeota are sulfur-preferred.

Microscopic image of the isolate.
(Photo: sinhhocvietnam)

However, studies using non-cultured methods show that a large number of Crenarchaeota live in cold seawater with oxygen. Molecular studies then discovered that low temperature Crenarchaeota is widely distributed in soil and water environments.

Crenarchaeota marine dominance - an estimated 10 ²⁸ cells in global waters - proves that they play an important role in the overall biochemical cycle. Indeed, radioactive isotope analysis of Crenarchaeota's lipids in the environment showed that they fixed inorganic C.

In this study, Konneke and his colleagues were the first to isolate the fixed neck N bacteria from the marine Crenarchaeota. This strain developed a self-healing chemolithoautotrophic by oxidizing ammonia aerobic to nitrite. The exchange of autotrophs and its close phylogenetic correlation with the sequences of Crenarchaeota in marine environments indicates that the Crenarchaeota N fixation at sea may be important for the marine species. Crenarchaeota (Photo: tolweb.org) shows the overall N and C.

This paper for the first time provides clear evidence of the existence of ammonia-oxidizing ancient bacteria. This ancient bacterium greatly transformed our understanding of the diversity, the range of life and the evolutionary history of prokaryote species that catalyzed the first step in the process of fixing N.

The authors isolated the ancient bacteria that oxidized autotrophic ammonia from seawater and showed that they were evolutionarily close to sea-type Crenarchaeota, a group previously discovered by molecular methods in one number of marine environment. Furthermore, this ammonia oxidation strain has genes that are similar to the genes that encode ammonia monooxygenase (an important enzyme needed for ammonia oxidation) of bacteria. These genes were previously discovered in the Crenarchaeota genenome in the sea and land, but when they are similar to the bacterial methane encoding monoxygenase (which functions differently from ammonia monooxygenase), organisms can exist.

Nguyen Xuan Hung