In traditional classification systems, bacteria were generally divided into two kingdoms: Eubacteria and Archaebacteria. However, molecular studies and advancements in genetic research have transformed our understanding of bacterial diversity.
Currently, many scientists and classifications recognize the existence of multiple groups of bacteria beyond these two kingdoms. Some classifications include up to 20 recognized phyla within the domain Bacteria alone, highlighting the immense diversity found within this group.
Eubacteria, or true bacteria, encompass a wide range of organisms, while Archaebacteria are distinct, often thriving in extreme environments. This separation indicates not only differences in cellular structure and genetics but also ecological niches they occupy.
In summary, while two kingdoms are a simplified view, modern classification recognizes that bacteria encompass multiple diverse groups, each with unique characteristics and functions in the ecosystem.