In microbiology, what best defines a pure culture?

• A. A population of microorganisms consisting of a single species or strain, free of contaminating organisms
• B. A sample taken directly from a natural environment without laboratory isolation
• C. A culture grown only on selective media to inhibit all microbial growth
• D. A mixed community of multiple microbial species growing together in the same medium

Answer: (A)

Verified step by step guidance

1. Understand that a pure culture in microbiology refers to a population of microorganisms that are genetically identical, meaning they belong to a single species or strain.
2. Recognize that a pure culture must be free from any contaminating organisms, ensuring that only one type of microorganism is present.
3. Differentiate a pure culture from a sample taken directly from a natural environment, which usually contains multiple species and is not isolated.
4. Note that selective media are used to inhibit the growth of certain microbes but do not guarantee a pure culture by themselves; they help in isolating specific organisms.
5. Identify that a mixed community contains multiple microbial species growing together, which is the opposite of a pure culture.