What are the characteristic features of spirochetes?
Spirochetes are gram-negative, motile, spiral bacteria, from 3 to 500 m (1 m = 0.001 mm) long. Spirochetes are unique in that they have endocellular flagella (axial fibrils, or axial filaments), which number between 2 and more than 100 per organism, depending upon the species.
How do spirochetes differ from other bacteria?
Spirochaetes are chemoheterotrophic in nature, with lengths between 3 and 500 μm and diameters around 0.09 to at least 3 μm. Spirochaetes are distinguished from other bacterial phyla by the location of their flagella, called endoflagella which are sometimes called axial filaments.
Do spirochetes bacteria have flagella?
Spirochetes, which are members of a group of gram-negative bacteria with a spiral or flat-wave cell body, also show flagella-dependent motility, but their flagella are hidden within the periplasmic space and are thus called periplasmic flagella (PFs).
How are spirochete arranged?
Spirochetes have a helical shape and flexible bodies. Spirochetes move by means of axial filaments, which look like flagella contained beneath a flexible external sheath but lack typical bacterial flagella. Examples: Leptospira species (Leptospira interrogans), Treponema pallidum, Borrelia recurrentis, etc.
What is spirochetes morphology?
Spirochetes are bacteria with a spiral morphology ranging from loose coils to a rigid corkscrew shape. The three medically important genera include the cause of syphilis, the ancient scourge of sexual indiscretion, and Lyme disease, a more recently discovered consequence of an innocent walk in the woods.
How do spirochetes and spirilla differ?
Spirochetes have a rigid, corkscrew shape while spirilla are helical and more flexible. Spirilla have an external flagella but spirochetes have axial filaments. The cell walls of bacteria are responsible for the shape of the bacteria and the difference in the Gram stain reaction.
What do spirochetes use the flagella for?
Like many other bacteria, the spirochetes use long, helical appendages known as flagella to move; however, the spirochetes enclose their flagella in the periplasm, the narrow space between the inner and outer membranes. Rotation of the flagella in the periplasm causes the entire cell body to rotate and/or undulate.
What are the morphological forms of bacteria?
Bacteria are complex and highly variable microbes. They come in four basic shapes: spherical (cocci), rod-shaped (bacilli), arc-shaped (vibrio), and spiral (spirochete) (Figure 1.3(A)).
What does spirilla bacteria look like?
Spirilla (sing. spirillum) shapes are curved-shaped bacteria which can range from a gently curved shape to a corkscrew spiral. Many spirilla are rigid and able to move. The length of rod-shaped bacteria is over 2–100 μm.
How do helical bacteria differ from spirochetes?
Spiral bacteria can be subclassified by the number of twists per cell, cell thickness, cell flexibility, and motility. The two types of spiral cells are spirillum and spirochete, with spirillum being rigid with external flagella, and spirochetes being flexible with internal flagella.
What is the typical characteristic of most bacterial plasma membranes?
The plasma membrane structure of most bacterial and eukaryotic cell types is a bilayer composed mainly of phospholipids formed with ester linkages and proteins. These phospholipids and proteins have the ability to move laterally within the plane of the membranes as well as between the two phospholipid layers. Figure 8.