Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the gram-staining method of bacterial differentiation.
Exotoxins are usually heat labile proteins secreted by certain species of bacteria that diffuse into the surrounding environment.
Endotoxins are heat-stable lipopolysaccharide-protein complexes that form structural components of the cell wall of gram-negative bacteria and are released only by cell lysis or death of bacteria.
Bacterial Flagella: Structure, importance and examples of flagellated bacteria Bacterial flagella are long, thin (about 20 nm) whip-shaped appendages that move bacteria toward nutrients and other attractants. The flagella are free at one end and attached to the cell at the other end. The flagella can never be seen directly under the light microscope, but only after staining with special flagella stains that increase its diameter. Flagella are usually found in gram-negative bacilli. Gram-positive rods […]
Bacterial spores are latent, highly resistant structures (that is, without metabolic activity) that form in response to adverse environmental conditions.
The bacterial capsule is a large structure of many bacteria. It is a layer of polysaccharide that is found outside the cell envelope and is therefore considered part of the outer envelope of a bacterial cell. It is a well organized coat, it does not wash easily, and it can be the cause of various diseases. The capsule has a 0.2 µm thick viscous layer firmly attached to the cell wall of some encapsulated bacteria. […]
Staphylococcus aureus is a Gram-positive, round-shaped bacterium that is a member of the Firmicutes, and it is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin.