ABSTRACT
With the advent of molecular methods, the distinction between identification, classification, and evolutionary relationships has become blurred. In bacteriology, a classification is simply a method of organizing information. This organization may have an underlying meaning, or no meaning at all. We could choose to classify bacteria on the color their colonies have when grown on agar plates, a classification that would give prominence to the few yellow and red colored bacteria, while the majority would be classified in a group of white to cream colony forms. In early microbiology, organisms were classified according to shape, with the bacillus shape (now also called a rod) forming the largest group, and cocci, filaments, and so on smaller ones. It is important to stress that classifications were arbitrary; however, they do still have a use today. Microbiologists classify organisms according to their growth properties (anaerobe, chemolithotroph, methylotroph, etc., Sections C2 and D1).
