The mos commonly used bioreactor is of stirring type. The stirrer facilitates

Options

A. Temperature control
B. Ph control
C. Oxygen availability
D. Product removal

Answer

### Step-by-Step Solution:

1. **Understanding Bioreactors**:
- Bioreactors are large vessels used for growing microorganisms, cells, or tissues in controlled conditions to produce desired products, such as enzymes, antibiotics, or biofuels.

2. **Types of Bioreactors**:
- There are various types of bioreactors, but the most commonly used type is the stirring type, which is designed to facilitate mixing of the contents.

3. **Function of the Stirrer**:
- The stirrer in a bioreactor plays a crucial role in maintaining optimal conditions for microbial growth and product formation. It helps in:
- **Temperature Control**: Ensuring that the temperature remains within the desired range for the organisms being cultured.
- **pH Control**: Mixing helps maintain a uniform pH throughout the reactor.
- **Oxygen Availability**: For aerobic organisms, oxygen is essential for their metabolism. The stirrer ensures that oxygen is evenly distributed throughout the culture medium.
- **Product Removal**: Facilitates the movement of products out of the culture medium.

4. **Importance of Oxygen Availability**:
- Many microorganisms require oxygen for their growth (aerobic organisms). The stirring action enhances the transfer of oxygen from the air into the liquid medium, ensuring that these organisms have sufficient oxygen for their metabolic processes.

5. **Conclusion**:
- Among the various functions of the stirrer in a stirring type bioreactor, the most critical one is to facilitate oxygen availability for aerobic organisms.

### Final Answer:
The stirrer in a stirring type bioreactor primarily facilitates **oxygen availability**.

---