When you read about structure of Bacterial cells, you might have learnt about flagella and different types of flagellar arrangements that are found in gram negative bacteria. In the same chapter you might have also read that, most of the Gram positive bacteria are atrichous (without flagella) so they are non-motile (Enterococcus gallinarum and E. casseliflavus/E. flavescens, the gram positive, catalase negative cocci, generally are motile. )
So when we talk about motility patterns of Bacteria, we mostly talk about Gram negative bacteria. Motility patterns of Gram negative bacteria is also used for the identification of bacteria.
So in this blog post, I am sharing information about characteristic motility patterns of some bacteria. You will also find information about those bacteria which become non-motile in specific conditions and about some great exceptions about motility characteristics;
- Alcaligenes are motile by peritrichous flagella.
- Campylobacters are small delicate, spirally curved, motile Gram negative bacteria. They show characteristic rapid corkscrew-like motility.
- E. coli: Most are motile by peritrichous flagella. Alkalescens-Dispar group i.e. A-D group is non-motile.
- Helicobacter: Helicobacter spp are motile by tuft of flagella (up to 4-7 sheathed flagella are present at one end).
- Listeria spp is motile with a characteristic tumbling and rotating motility in broth cultures. when grown at 18- 25°C but not motile or minimally motile when grown at 35-37°C.
- Proteus (P. mirabilis and P. vulgaris) are actively motile (swarming motility). Motility
is not as easily observed at 35–37 ºC as at room temperature (20–28 ºC).
- Pseudomonas spp: Most species of Pseudomonas are motile except Pseudomonas malli by means of one or more flagella.
- Salmonella spp: Most strains are motile except Salmonella Gallinarum and Salmonella Pullorum
- Spirilla are motile with groups of flagella at both ends.
- Spirochaetes (Treponema, Borrelia, Leptospira): Are motile by bending and rotating body movements.
- Trophozoites of protozoan parasites Entamoeba histolytica, Giardia lamblia and Trichomonas vaginalis (move by flagella and an undulating membrane) etc shows motility in wet preparation.
- Vibrio cholerae: Vibrio cholerae are motile with single polar flagellum and shows rapid darting (“Shooting Star”) type of motility.
- Yersinia enterocolitica is motile when grown at 20- 28°C but non-motile when grown at 35-37°C.