Stirred Tank Bioreactor

Definition

A stirred tank bioreactor is a type of vessel used for the cultivation of microorganisms, cells, or enzymes, where mixing is achieved through mechanical agitation. This design promotes uniform distribution of nutrients and gases, which is essential for optimal growth and production in biochemical processes. The ability to control environmental conditions such as temperature, pH, and dissolved oxygen levels makes stirred tank bioreactors a widely used choice in both research and industrial applications for bioprocessing.

5 Must Know Facts For Your Next Test

1. Stirred tank bioreactors are characterized by their use of an impeller or agitator to mix the culture medium and maintain homogeneity.
2. They can be designed in various scales, from laboratory-scale to industrial-scale, allowing for flexibility in experimentation and production.
3. Control systems integrated into stirred tank bioreactors can monitor and adjust key parameters like temperature, pH, and dissolved oxygen in real-time.
4. The design often includes features such as baffles to enhance mixing efficiency and minimize dead zones within the reactor.
5. These bioreactors can operate under batch, fed-batch, or continuous modes, allowing for various production strategies based on the desired outcome.

Review Questions

• How does the design of a stirred tank bioreactor facilitate optimal growth conditions for microorganisms?
  • The design of a stirred tank bioreactor promotes optimal growth by ensuring uniform mixing of nutrients and gases throughout the culture medium. The mechanical agitation from the impeller helps to maintain homogeneity and prevent sedimentation of cells. Additionally, real-time monitoring and control of parameters like temperature and pH ensure that the environmental conditions remain favorable for microbial activity, enhancing overall productivity.
• Discuss the role of mass transfer in the operation of stirred tank bioreactors and how it impacts the efficiency of biochemical processes.
  • Mass transfer is critical in stirred tank bioreactors as it involves the movement of substrates, oxygen, and other nutrients from the bulk fluid to the cells. Efficient mass transfer maximizes substrate utilization and waste removal, which directly affects the growth rate and product yield of microorganisms. Optimizing mass transfer through reactor design features such as baffles and appropriate agitation speeds can significantly enhance the efficiency of biochemical processes.
• Evaluate the advantages and limitations of using stirred tank bioreactors in large-scale industrial applications compared to other types of reactors.
  • Stirred tank bioreactors offer several advantages in large-scale industrial applications, such as excellent mixing capabilities, ease of control over environmental parameters, and scalability from lab to production levels. However, they also have limitations like higher operational costs and potential shear sensitivity for certain cells. Comparing them to other reactor types, such as bubble column reactors or fixed-bed reactors, highlights these trade-offs; while alternatives may provide lower shear environments or better gas-liquid interactions, they often lack the precise control offered by stirred tanks.

Related terms

Fermentation:

A metabolic process that converts sugars to acids, gases, or alcohol using microorganisms, often carried out in bioreactors.

Mass Transfer:

The movement of substances from one phase to another, crucial in bioreactors for efficient nutrient delivery and waste removal.

Kinetics: The study of the rates of chemical processes, including biological reactions occurring in bioreactors.