Eubacteria A kingdom (or subkingdom) of prokaryotic organisms that comprise present-day bacteria. They include aerobic and anaerobic species and occur in virtually all habitats. Some live in or on the bodies of other organisms, and may cause disease.ubacteria are prokaryotic, meaning their cells do not have defined, membrane-limited nuclei. As a group they display an impressive range of biochemical diversity, and their numerous members are found in every habitat on Earth.