Question

Discuss several reasons why growing a microorganism in a pure culture is valuable and what you would not be able to learn from studying a microorganism in pure culture.

Answer 1

In microbiology experiments, pure cultures are obtained by taking a single microbe and inoculating it in either agar media or a nutrient liquid media or broth. They replicate and form colonies of organisms which are genetically similar because they are the clones of a single micro organism. From a mixed bacterial culture also a pure culture can be obtained by separating the cells by serial dilution method and growing them on the nutrient media and isolate them individually.

Pure cultures are important to study morphological characteristics of any species of the micro organisms.

To perform biochemical tests on the micro organism, mixed cultures cannot give accurate results because they have different species reacting differently.

For testing antibiotic resistance of a particular micro organism only pure cultures should be used because the presence of other species may cause a change in the growth of the species that has to be tested upon.

Many other physiological processes can be studied only using pure cultures.

Sometimes mixed culture is important to enhance the growth of one species by the other species so the effects of one species on the other can be studied only using mixed cultures and comparison between two or more species reacting to any biochemical substance cannot be studied using pure cultures so mixed cultures are used.