Abstract
Various nitrogen-fixing cyanobacteria, such as Anabaena, Calothrix, Nostoc, Scytonema, and Synechococcus (Cyanothece), have been used for biological molecular hydrogen production. These nitrogen-fixing cyanobacteria are morphologically divided into three major groups, heterocystous filamentous, non-heterocystous filamentous and unicellular. Hydrogen production mechanism in each group is slightly different relating to these morphological differences. Relationship between the hydrogen productivity and phylogeny of these cyanobacteria has not been elucidated well. We analyzed the molecular phylogeny of nitrogen-fixing marine cyanobacteria in our culture collection. At the same time, hydrogen productivity for each strain was also measured. The results suggested that the hydrogen productivity of cyanobacteria might be fixed genetically in each clade. At this symposium we will discuss about the relationships between the hydrogen productivity and molecular phylogeny of cyanobacteria and also propose the possible task of molecular phylogenetic analysis for the screening of cyanobacteria baring high hydrogen productivity.
