A proposal for the unification of five species of the cyanobacterial genusMicrocystis Kutzing ex Lemmermann 1907 under the Rules of the Bacteriological Code

Genomic DNA homologies were examined from six Microcystis (cyanobacteria) s trains, including five different species, Microcystis aeruginosa, Microcyst is ichthyoblabe, Microcystis novacekii, Microcystis viridis and Microcystis wesenbergii, All DNA-DNA reassociation values between two strains of M, ae ruginosa and the other four species exceeded 70 %, which is considered high enough for them to be classified within the same bacterial species. It is proposed to unify these five species into M. aeruginosa under the Rules of the Bacteriological Code and NIES843(T) (= IAM M-247(T)) is proposed as the type strain. Two other species, Microcystis flos-aquae and Microcystis pse udofilamentosa, should be regarded as morphological variations of this unif ied M. aeruginosa, The current taxonomy of cyanobacteria depends too much u pon morphological characteristics and must be reviewed by means of bacterio logical methods as well as traditional botanical methods.