Which of the following is NOT considered a phenotypic trait of bacteria?

• A. Gram reaction
• B. Motility
• C. Cell shape
• D. 16S rRNA gene sequence

Answer: (D)

Verified step by step guidance

1. Understand the difference between phenotypic and genotypic traits: Phenotypic traits are observable characteristics of bacteria, such as morphology, staining properties, and behavior, while genotypic traits relate to the genetic makeup, such as DNA or RNA sequences.
2. Identify the traits listed: Gram reaction, motility, and cell shape are all observable characteristics that can be seen under a microscope or through specific staining and testing methods, making them phenotypic traits.
3. Recognize that the 16S rRNA gene sequence is a molecular characteristic derived from the bacterial genetic material, used for identifying and classifying bacteria based on their genetic information, which is a genotypic trait, not phenotypic.
4. Conclude that since the 16S rRNA gene sequence is based on genetic analysis rather than observable physical or behavioral characteristics, it is NOT considered a phenotypic trait.
5. Therefore, when asked which is NOT a phenotypic trait, the correct choice is the 16S rRNA gene sequence because it represents a genotypic characteristic.