Why are stirred-tank bioreactors advantageous over shake flasks in biotechnological processes?

Offer better aeration and mixing properties.

The correct answer is:

(b) provide better aeration and mixing properties.

Explanation: Stirred-tank bioreactors offer several advantages over shake flasks when it comes to culturing microorganisms and producing biotechnological products:

1. Better Aeration: Stirred-tank bioreactors provide efficient aeration of the culture medium. The stirrers or agitators inside the bioreactor ensure even distribution of oxygen throughout the culture, which is essential for aerobic microorganisms. This leads to improved oxygen availability and utilization by the cells, promoting higher cell growth and productivity.
2. Better Mixing Properties: The agitation in stirred-tank bioreactors ensures thorough mixing of the culture medium, nutrients, and microorganisms. This results in a more homogeneous distribution of the cells and nutrients, reducing the risk of concentration gradients and ensuring a consistent environment for the microorganisms to grow and produce desired products.
3. Scalability: Stirred-tank bioreactors are easily scalable, making them suitable for large-scale production. They can handle larger volumes of culture compared to shake flasks, making them ideal for industrial-scale bioprocessing.
4. Better Control: Stirred-tank bioreactors offer better control over various parameters like temperature, pH, dissolved oxygen, and nutrient concentrations. This precise control enables researchers to optimize culture conditions for maximum productivity and product yield.
5. Online Monitoring: Stirred-tank bioreactors are equipped with sensors and monitoring systems that allow for real-time online monitoring of various parameters. This data helps researchers to make timely adjustments and optimize the culture conditions during the fermentation process.
6. Reduced Contamination Risk: The closed and controlled design of stirred-tank bioreactors reduces the risk of contamination from external sources, ensuring a more sterile environment for cell culture.

In contrast, shake flasks are simple and low-cost containers used in laboratory settings. While shake flasks are suitable for small-scale experiments and preliminary studies, they lack the sophisticated control, aeration, and mixing capabilities of stirred-tank bioreactors, making them less efficient for large-scale industrial production and precise bioprocessing.