Gram(-) bacterium is

Options

A. Streptomyces coelicolor
B. Escherichia coli
C. Ampycolatopsis orientalis
D. Bacillus subtilis.

Answer

To determine which of the given options is a Gram-negative bacterium, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Gram Staining Technique**:
- Gram staining is a method used to classify bacteria into two groups: Gram-positive and Gram-negative.
- Gram-positive bacteria retain the crystal violet stain and appear purple under a microscope, while Gram-negative bacteria do not retain the stain and appear pink due to the counterstain (safranin).

2. **Identify the Characteristics of Gram-negative Bacteria**:
- Gram-negative bacteria have a thinner peptidoglycan layer in their cell wall and an outer membrane containing lipopolysaccharides.

3. **Review the Given Options**:
- The options provided are:
- A) Streptomyces colicolor
- B) E. coli
- C) M. pycolaptor colitopsis
- D) Orientalis
- E) Bacillus subtilis

4. **Analyze Each Option**:
- **Streptomyces colicolor**: This is a Gram-positive bacterium.
- **E. coli**: This is a well-known Gram-negative bacterium.
- **M. pycolaptor colitopsis**: This is not a commonly recognized bacterium, but it is likely not Gram-negative.
- **Orientalis**: This does not specify a known bacterium and is ambiguous.
- **Bacillus subtilis**: This is a Gram-positive bacterium.

5. **Determine the Correct Answer**:
- Based on the analysis, the only Gram-negative bacterium from the options is **E. coli**.

### Final Answer:
**E. coli** is a Gram-negative bacterium.

---