Chapter IV Motility

Publisher Summary In the microbial world, motile organisms are distributed in most of the phyla. The mode of movement differs in different microbial groups and has been regarded as an important characteristic for the identification of microbes. Myxomycetes, slime moulds, and some unicellular protozoa move over the surface of solid substances as a result of cytoplasmic movement. This kind of movement is commonly called amoeboid movement. Another movement that is possible only when organisms are in contact with a solid surface is the gliding movement, such as seen with myxobacteria, blue-green algae, and some of the filamentous bacteria such as the Beggiatoales. Many motile micro-organisms can move actively in a liquid medium. This swimming movement is brought about by locomotive organelles known as flagella or cilia. Flagella of eubacteria differ in their fine structure from those found in eukaryotic micro-organisms, such as flagellates or protozoa. Among the bacteria, spirochetes swim in a liquid medium with the aid of an axial filament. This chapter describes the techniques that concern the observation of motility and locomotive organelles of eubacteria.