https://www.sinica.edu.tw/en/news/7341

Dr. Wen-Hsiung Li and colleagues at the Biodiversity Research Center, Academia Sinica, Taiwan, have published a study that overturns the conventional hypothesis on the origin and evolution of nitrogen fixation in organisms. Previous studies had postulated that nitrogen fixation first evolved in archaea and then transferred to eubacteria. However, nitrogen-fixing eubacteria are much more abundant and more diverse in their ecological status than nitrogen-fixing archaea. Dr. Lee’s team proposed the “bacteria-first” theory, which postulates that nitrogen fixation evolved first in eubacteria and then transferred to archaea. After analysing more than 30,000 prokaryotic genomes and identified six genes involved in nitrogen fixation in all the prokaryotic genomes they analyzed. They reconstructed multiple phylogenetic trees using these genes and found strong support for the eubacterial prior theory.