Stirred-tank bioreactors have been designed for :

Options

A. purification of product
B. addition of preservatives to the product
C. availability of oxygen throughout the process
D. ensuring anaerobic conditions in the culture vessel

Answer

**Step-by-Step Solution:**

1. **Understanding Bioreactors**: Bioreactors are vessels designed to support a biologically active environment. They are used to grow organisms or cells that produce a desired product, such as proteins, enzymes, or other biochemicals.

2. **Purpose of Stirred-Tank Bioreactors**: Stirred-tank bioreactors are specifically designed to produce large quantities of biological products. When small-volume cultures are insufficient for commercial production, stirred-tank bioreactors provide a solution by allowing for larger scale cultivation.

3. **Design Features**: These bioreactors are typically cylindrical in shape and equipped with stirring mechanisms (blades) that mix the contents. This stirring ensures that all components are evenly distributed and that the cells or organisms have adequate access to nutrients.

4. **Oxygen Availability**: One of the critical functions of stirred-tank bioreactors is to maintain adequate oxygen levels. The stirring action not only mixes the contents but also enhances the transfer of oxygen into the liquid medium, which is essential for aerobic organisms.

5. **Conclusion**: Therefore, stirred-tank bioreactors have been designed primarily for the effective mixing of culture contents and to ensure the availability of oxygen throughout the fermentation or cultivation process.

**Final Answer**: Stirred-tank bioreactors have been designed for the effective mixing of culture contents and to ensure the availability of oxygen throughout the process.

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