EUBACTERIUM

plural Eubacteria, any of a group of true bacteria, one of two major groups of prokaryotic organisms. The other group, the archaebacteria, are as different from eubakteria as either is from the eukaryotes. The division of the bacteria into two groups has been suggested by ribosomal RNA studies of the genetic information of the organisms. Eubacteria and archaebacteria are thought to have evolved separately from a common ancestor early in Earth's history. Eubacteria and archaebacteria differ in important characteristics, such as the number of ribosomal proteins and the size and shape of the ribosomal S unit. See bacterium; archaebacterium.