What are the most common methods for monitoring and controlling bioreactor parameters?

1 Temperature control

Temperature is a critical factor that affects the metabolism, growth, and productivity of bioreactor cultures. Temperature control is usually achieved by using a heating or cooling jacket, coil, or plate that surrounds the bioreactor vessel. Alternatively, some bioreactors use internal or external heat exchangers that circulate a heating or cooling fluid through the bioreactor. The temperature is measured by a thermocouple or a resistance temperature detector (RTD) that sends a signal to a controller that adjusts the heating or cooling device accordingly. The optimal temperature range depends on the type of organism and the bioprocess objectives, but it is typically between 25°C and 40°C for most microbial and mammalian cells.

2 pH control

pH is another important parameter that influences the enzymatic activity, cell viability, and product stability of bioreactor cultures. pH control is usually achieved by adding acid or base solutions to the bioreactor through automated pumps or valves. The pH is measured by a pH electrode that sends a signal to a controller that regulates the acid or base addition. The optimal pH range also depends on the type of organism and the bioprocess objectives, but it is usually between 5 and 8 for most microbial and mammalian cells.

3 Dissolved oxygen control

Dissolved oxygen (DO) is the amount of oxygen available in the bioreactor liquid phase for the respiration of aerobic organisms. DO control is usually achieved by adjusting the flow rate and composition of the gas supply to the bioreactor, as well as the agitation speed of the impeller. The DO is measured by a DO probe that sends a signal to a controller that modifies the gas flow rate or the agitation speed. The optimal DO level varies depending on the oxygen demand and tolerance of the organism and the bioprocess objectives, but it is generally between 20% and 50% of air saturation for most microbial and mammalian cells.

4 Agitation control

Agitation is the process of mixing the bioreactor contents to enhance mass transfer, heat transfer, and homogeneity. Agitation control is usually achieved by varying the speed of the impeller or the power input to the motor. The agitation speed or power is measured by a tachometer or a torque meter that sends a signal to a controller that adjusts the impeller speed or power. The optimal agitation level depends on the rheology, viscosity, and shear sensitivity of the bioreactor culture, as well as the bioprocess objectives, but it is typically between 100 and 1000 rpm for most microbial and mammalian cells.

5 Nutrient control

Nutrient is the term used to describe the essential components of the bioreactor medium that support the growth and metabolism of the bioreactor culture, such as carbon, nitrogen, phosphorus, sulfur, vitamins, minerals, and trace elements. Nutrient control is usually achieved by adding nutrient solutions to the bioreactor through automated pumps or valves. The nutrient concentration is measured by various sensors or analyzers that send signals to controllers that regulate the nutrient addition. The optimal nutrient concentration depends on the specific requirements and kinetics of the organism and the bioprocess objectives, but it is usually maintained at a level that avoids nutrient limitation or excess.

6 Here’s what else to consider

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