In bacterial taxonomy, what is meant by a "strain" of bacteria?

• A. A taxonomic rank above species that includes multiple related genera
• B. A group of bacteria that share the same genus but belong to different species
• C. A genetic variant or subtype within a bacterial species, typically derived from a single isolate or colony
• D. Any bacterial cell type defined solely by its shape (e.g., coccus, bacillus, spirillum)

Answer: (C)

Verified step by step guidance

1. Understand that in bacterial taxonomy, the term 'strain' refers to a classification below the species level.
2. Recognize that a strain represents a genetic variant or subtype within a bacterial species, meaning it is a group of bacteria that share most characteristics but have some genetic differences.
3. Note that strains are typically derived from a single isolate or colony, which means they originate from one bacterial cell or a group of genetically identical cells.
4. Differentiate 'strain' from higher taxonomic ranks such as genus or species, which group bacteria based on broader similarities.
5. Also distinguish 'strain' from classifications based solely on morphology (shape), such as coccus or bacillus, which do not define genetic differences.