On the basis of shape and staining Escherichia coli is

Options

A. Bacillus, Gram (-)ve
B. Coccus, Gram (-)ve
C. Spirillum, Gram (+)ve
D. Vibrio, Gram ( + )ve

Answer

**Step-by-Step Solution:**

1. **Understanding the Organism**: Escherichia coli, commonly known as E. coli, is a type of bacteria that belongs to the kingdom Monera. It is essential to determine its characteristics based on shape and staining properties.

2. **Gram Staining Process**: The Gram staining technique is used to classify bacteria into two groups: Gram-positive and Gram-negative. This classification is based on the structure of the bacterial cell wall.

3. **Cell Wall Structure**: E. coli has a thin layer of peptidoglycan surrounded by an outer lipid membrane. This structure is characteristic of Gram-negative bacteria.

4. **Staining Result**: During the Gram staining process, E. coli does not retain the crystal violet stain due to its thin peptidoglycan layer and the presence of the outer membrane. Instead, it takes up the counterstain (usually safranin), which gives it a pink appearance.

5. **Shape of E. coli**: In terms of shape, E. coli is rod-shaped, which is classified as "bacillus."

6. **Conclusion**: Based on the shape and staining properties, E. coli is classified as a Gram-negative bacillus.

**Final Answer**: E. coli is a bacillus and Gram-negative.

---