Outer layer of lipopolysaccharide is characteristic of

Options

A. Gr `o+` rods
B. Gr `Theta` rods
C. Gr `o+` cocci
D. all

Answer

To answer the question regarding the outer layer of lipopolysaccharide, we can break down the information as follows:

### Step-by-Step Solution:

1. **Understanding Lipopolysaccharides (LPS)**:
- Lipopolysaccharides are large molecules consisting of a lipid portion and a polysaccharide portion. They are found in the outer membrane of certain bacteria.

2. **Identifying Bacterial Types**:
- There are two main types of bacteria based on their cell wall structure: Gram-positive and Gram-negative bacteria.
- Gram-negative bacteria have a distinctive outer membrane that contains lipopolysaccharides.

3. **Characteristics of Gram-negative Bacteria**:
- Gram-negative bacteria have a thin layer of peptidoglycan surrounded by an outer membrane.
- The outer membrane is composed of lipopolysaccharides, which serve as a barrier and are important for the structural integrity of the bacteria.

4. **Comparison with Gram-positive Bacteria**:
- Gram-positive bacteria do not have an outer membrane. Instead, they possess a thick peptidoglycan layer.
- This distinction is crucial as it helps in identifying the type of bacteria based on their cell wall composition.

5. **Conclusion**:
- Since the outer layer of lipopolysaccharide is characteristic of Gram-negative bacteria, we conclude that the correct answer is Gram-negative rods.

### Final Answer:
The outer layer of lipopolysaccharide is characteristic of **Gram-negative rods**.

---