cyanobacterium (genus) cyanobacterium (genus) cyanobacterium genus of cyanobacteria. cyanobacterium scientific classification domain: bacteria phylum: cyanobacteria class: cyanophyceae order: chroococcales family: cyanobacteriaceaekomárek et al. 2014 genus: cyanobacteriumrippka & cohen-bazire 1983