All living things are classified in a scheme wherein categories represent successively dependent and related groups. The highest possible levels are designated kingdoms. For years, the traditional two were the plant and animal kingdoms. Today there is a change in this approach.
The lower forms of life variably incorporate features of both plants and animals and […]

Biochemical Reactions
Biochemical tests demonstrate the presence of enzyme systems within the microbial cell, such as those responsible for the fermentation of carbohydrates or the decomposition of proteins and are done so that individual species of microbes may be identified. By noting the presence of specific enzymes in a pure culture of bacteria being studied under […]

Bacteria can be best examined and studied under the microscope. It may be desirable to examine unstained bacteria to determine their biologic grouping, motility, and reaction and chemicals or specific sera. These properties may be determined in a hanging drop preparation or in a wet mount. A few species of bacteria that cannot be stained […]

Nucleus
As special staining methods designed to visualize the chemical substances making up the nucleus in the higher forms of life were applied to the study of bacteria, it became evident that bacteria contained nuclear material. This was seen in electron micrographs as a distinct and relatively transparent structure of rounded proportions with no detectable nuclear […]

For preparation of a streak plate, a single loopful of infectious material is streaked over the surface of the solid medium (agar) in a Petri dish. There are several ways to do this. The patterns are widely used and give good separation of colonies, which can then be used for subculturing.
Bacterial Plate Count
The […]

One important concept in microbiology is attenuation. Attenuation is a form of adaptation which indicates a loss in the disease ability of a specific organism. When an organism whose virulence is decreased, it is said to be attenuated. A highly pathogenic organism may be rendered temporarily or permanently nonpathogenic if repeatedly subcultured on artificial […]