Nitrogen-Fixing Blue—Green Algae

Abstract

Blue—green algae (Cyanobacteria) are a special group of prokaryotes. They have chlorophyll and phycobiliprotein and can fix carbon by oxygen-evolution photosynthesis like plants; and their genome contains nucleotide sequences which are comparable with that of 16S and 5S rRNA of cubacteria. Therefore, in tradition, they are called Cyanophyta (Myxophyta, Cyanophyceae), but in the recent decade, they are also called Cyanobacteria. (According to the “Manual of Systematic Bacteriology” Vol. 3 (1989), they can be called cyanobacteria or blue—green algae or Cyanophyceae). For convenience, I use BGA (blue—green algae) for these prokaryotes in this paper. BGA are widely distributed all over the earth. While fixing carbon from CO2, certain BGA can fix dinitrogen from the atmosphere, and are called nitrogen-fixing BGA, including free living and symbiotic forms.