Bioreactor

What is a bioreactor?

A bioreactor is a system designed to maintain controlled conditions for cultivating cells, microorganisms or tissues and performing biological reactions. It creates an environment in which parameters such as temperature, pH, dissolved oxygen, agitation and feeding can be monitored and adjusted according to the requirements of the bioprocess.

Bioreactors are used in laboratories, research centers and industrial facilities to produce medicines, vaccines, recombinant proteins, enzymes, biomass, fermented foods, biofuels and other biotechnology products. They can also support biological wastewater treatment and the development of new fermentation processes.

How does a bioreactor work?

A bioreactor works by providing the conditions required by the cultivated organism or cell line. The vessel contains a culture medium with nutrients and may be connected to sensors, pumps, gas lines, heating and cooling systems, and an agitation mechanism.

During cultivation, a control system receives information from the sensors and adjusts the operating conditions to keep the process within programmed limits. Commonly monitored parameters include:

• culture temperature;
• pH and dissolved oxygen;
• agitation speed;
• gas composition and flow rate;
• pressure and foam formation;
• addition of nutrients, acids, bases and antifoam agents.

In aerobic processes, agitation and aeration improve oxygen transfer into the culture medium. In anaerobic processes, the system must limit or exclude oxygen. The appropriate configuration depends on the microorganism, cell line and intended product.

Main types of bioreactors

The stirred-tank bioreactor is one of the most widely used designs. It contains one or more impellers that mix the vessel contents and promote mass transfer. Other designs include bubble-column, airlift, packed-bed, fluidized-bed and single-use bioreactors, as well as photobioreactors.

Microbioreactors operate with small volumes and are primarily used for strain screening and early process development. Larger systems support detailed characterization, scale-up, pilot production and industrial manufacturing.

Bioreactor operating modes

• Batch: the main components are added at the beginning, with no continuous nutrient feed during cultivation.
• Fed-batch: nutrients are added during the process to control growth and product formation.
• Continuous: fresh medium enters the system while part of the culture is continuously removed.
• Perfusion: the culture medium is renewed while cells are retained inside the bioreactor.

Bioreactor applications in laboratories and industry

In research laboratories, bioreactors are used to investigate growth kinetics, optimize culture media, compare feeding strategies and generate scale-up data. Pharmaceutical and biotechnology companies use them to manufacture antibodies, vaccines, recombinant proteins, viral vectors, antibiotics and enzymes.

Bioreactors are also applied in food, beverage, agriculture, energy and environmental operations. Yeast fermentation, probiotic production, microalgae cultivation and biological wastewater treatment are common examples.

What is the difference between a bioreactor and a fermenter?

A fermenter is traditionally associated with the cultivation of microorganisms, whereas bioreactor is a broader term that may include animal cells, plant cells, microorganisms, tissues and enzymes. In microbial processes, the two terms are sometimes used interchangeably.

What is the difference between a bioreactor and a microbioreactor?

The primary differences are scale and parallelization. Microbioreactors use small working volumes to compare many conditions simultaneously. Conventional bioreactors offer larger volumes and are commonly used for characterization, validation and scale-up.

Which parameters should be controlled in a bioreactor?

The required parameters depend on the process, but commonly include temperature, pH, dissolved oxygen, agitation, aeration, pressure, foam and feeding. Proper control supports cell growth, product formation and cultivation reproducibility.