- "a group of extremely metabolically diverse, prokaryotic, unicellular microorganisms usually possessing cell walls, sometimes forming filaments, which are found in soil, water or parasitic or saprophytic on plants and animals, the parasitic forms causing many familiar infectious diseases. They reproduce by binary fission or asexual spores and also transfer genetic material by sexual processes (conjugation) and by virus (bacteriophage)-mediated transfer (transduction). They comprise the "true" bacteria (eubacteria), the "archaebacteria", the actinomycetes and related organisms, mycoplasmas, rickettsias and rickettsia-like organisms, and spirochaetes.."(B73)

• Singular Bacterium