Question

Which of the following is the example of Gram-negative bacteria?

• A. Lactobacillus
• B. Escherichia coli
• C. Bacillus subtilis
• D. Staphylococcus aureus

Hint:

Differentiate between Gram-positive and Gram-negative bacteria based on cell wall structure and staining properties.

Answer 1

The Correct Option is B

Gram-negative bacteria are characterized by having a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides. This structure gives them a pink color when subjected to the Gram staining technique. Among the options provided:
1. Lactobacillus: A Gram-positive bacterium, commonly found in probiotics and involved in lactic acid fermentation.
2. Escherichia coli (E. coli): A Gram-negative bacterium found in the gut of warm-blooded organisms. It is distinguished by its thin peptidoglycan wall and outer membrane.
3. Bacillus subtilis: A Gram-positive bacterium, widely studied and used in industrial processes.
4. Staphylococcus aureus: Another Gram-positive bacterium, known for causing infections like MRSA. Thus, the correct answer is Escherichia coli, which is a well-known Gram-negative bacterium.