Question

How might fluorescence microscope be used to visualize the bacterial capsule?

a. By directly capturing capsule fluorescence
b. By using phase-contrast imaging
c. By employing immunofluorescence staining
d. By increasing the microscope's magnification

Answer 1

To visualize the bacterial capsule, a fluorescence microscope is used with immunofluorescence staining, employing fluorochrome-labeled antibodies that specifically bind to the capsule's antigens.

Step-by-step explanation:

A fluorescence microscope can be used to visualize the bacterial capsule by employing immunofluorescence staining. In this method, fluorochrome-labeled antibodies are used to bind to the bacterial capsule antigens. Direct immunofluorescence attaches the stain directly to primary antibodies that bind to the antigen of interest. Indirect immunofluorescence uses secondary antibodies that bind to primary antibodies, which in turn, bind to the antigen.

Magnification alone cannot help in visualizing the capsule as it does not provide the necessary contrast; instead, immunofluorescence assays and specific fluorescent dyes are used for easy and rapid detection of these structures. When it comes to viewing thick structures such as biofilms, a confocal scanning laser microscope is especially useful because it can focus on one z-plane at a time and produce a three-dimensional image.