Motility Patterns of Bacteria

When you read about the structure of bacterial cells, you might have learned about flagella and the different types of flagellar arrangements found in gram-negative bacteria. Most 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 it’s about bacterial motility, we mostly discuss Gram-negative bacteria. Motility patterns of Gram-negative bacteria are also used for their identification.

You might have appreciated the colony of Proteus spp in blood agar and MacConkey agar and identified it with its characteristics swarming patterns.

So in this blog post, I am sharing information about the 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 to motility characteristics;

Characteristics types of  Bacterial Motility

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 is motile by a tuft of flagella (up to 4-7 sheathed flagella are present at one end).

Listeria spp: It 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 spp: 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 using 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 and Giardia lamblia (move by flagella and an undulating membrane) etc show motility in wet preparation.

Vibrio cholerae: Vibrio cholerae are motile with the single polar flagellum and show rapid darting  (“Shooting Star”) motility.

Yersinia enterocolitica is motile when grown at 20- 28°C but non-motile at 35-37°C.

References

1. Madigan Michael T, Bender, Kelly S, Buckley, Daniel H, Sattley, W. Matthew, & Stahl, David A. (2018). Brock Biology of Microorganisms (15th Edition). Pearson.
2. Color Atlas and Textbook of Diagnostic Microbiology, Koneman, 5th edition