In order to isolated the DNA from a suspension of Bacillus subtilis, which of the following enzymes will be required to break and open the cells ?

Options

A. Cellulase
B. Lysozyme
C. Chitinase
D. Ribonuclease

Answer

To isolate DNA from a suspension of Bacillus subtilis, we need to break open the bacterial cells. The correct enzyme required for this process is lysozyme. Here’s a step-by-step breakdown of the reasoning:

### Step-by-Step Solution:

1. **Understanding the Requirement**:
- We need to isolate DNA from Bacillus subtilis, which is a type of bacteria. To do this, we must first break open the bacterial cells to access the DNA inside.

2. **Analyzing the Options**:
- The options provided are:
- A) Cellulase
- B) Lysozyme
- C) Chitinase
- D) Ribonuclease

3. **Evaluating Cellulase**:
- **Cellulase** is an enzyme that breaks down cellulose, which is a component of plant cell walls. Since bacteria do not have cellulose in their cell walls, cellulase would not be effective in breaking open Bacillus subtilis cells.
- **Conclusion**: Incorrect option.

4. **Evaluating Lysozyme**:
- **Lysozyme** is an enzyme that specifically targets the peptidoglycan layer of bacterial cell walls. By cleaving this layer, lysozyme can effectively lyse (break open) bacterial cells, thus allowing access to the DNA.
- **Conclusion**: This is the correct enzyme needed for breaking open the cells.

5. **Evaluating Chitinase**:
- **Chitinase** breaks down chitin, which is found in the cell walls of fungi, not bacteria. Since Bacillus subtilis does not contain chitin, this enzyme would not be useful for our purpose.
- **Conclusion**: Incorrect option.

6. **Evaluating Ribonuclease**:
- **Ribonuclease** is an enzyme that degrades RNA. While it can be useful in later stages of DNA isolation to remove RNA contaminants, it does not play a role in breaking open the cells. Therefore, it is not suitable for this initial step.
- **Conclusion**: Incorrect option.

7. **Final Conclusion**:
- The enzyme required to break and open the cells of Bacillus subtilis for DNA isolation is **lysozyme**.

### Final Answer:
**B) Lysozyme**