Bioreactors: Unraveling the Core Modern Biotechnology's Indispensable Role in Transforming Healthcare and Agriculture

 

Bioreactors

What are Bioreactors?

Biological reactor are vessels in which biological reactions are carried out under controlled conditions. Biological reactor are now widely used in bioprocessing and biotechnology applications like the production of antibiotics, hormones, vaccines, monoclonal antibodies, recombinant proteins and other therapeutic agents. They have revolutionized industries like pharmaceuticals, wastewater treatment, food processing, and more.

Types of Bioreactors

There are different types of biological reactor categorized based on their mode of operation, configuration, application, etc.:

Batch Biological reactor

Batch Bioreactors reactor are simple vessels in which the entire reaction occurs at once. A batch bioreactor involves adding all the necessary components like microorganisms, nutrient media, buffers at the start and allowed the reaction to proceed until completion. They are simple and useful for experiments and small-scale production.

Continuous Stirred Tank Biological reactor (CSTR)

In continuous stirred tank biological reactor (CSTR), the reaction medium is constantly stirred while fresh medium is continuously fed and an equal amount of fermented broth containing biomass, metabolites, and by-products is removed simultaneously on a continuous basis. CSTRs allow prolonged and large-scale production of bioproducts.

Packed Bed Biological reactor

Packed bed biological reactor contain immobilized cells packed in a column. The substrate flows through this packed bed where the immobilized cells metabolize it. These are useful when continuous processing is required with immobilized cells.

Fluidized Bed Biological reactor

Fluidized bed biological reactor have immobilized cells in a porous or expanded material that is kept in suspension by the upward flow of nutrients and gases. They provide excellent mass transfer and are useful on an industrial scale.

Components and Parameters

Biological reactor contain specialized components to carefully control various parameters:

Agitators/Impellers - Used for uniform mixing, mass transfer, and prevention of settling in stirred tank biological reactor.

Sensors - Electrochemical sensors monitor pH, dissolved oxygen (DO), temperature, and pressure inside biological reactor.

Gas Mixing Systems - Spargers and agitators are used to distribute air or oxygen to stir cells and provide vital gases.

Sampling Ports - Allow periodic sampling to check cell growth, metabolite production without disturbing processes.

Controllers - PID controllers regulate parameters like pH, DO to precise setpoints using pumps, valves, stirrers, heat exchangers.

Heat Exchangers - Maintain optimum temperature conditions inside biological reactor via cooling/heating jackets or internal coils.

Applications of Biological reactor

Biological reactor have myriad industrial and research applications harnessing diverse microorganisms:

Production of Antibiotics - Commercial production of semi-synthetic and synthetic antibiotics like penicillin via fungi biological reactor.

Brewing - Beer and alcohol production through carefully monitored yeast fermentation in large biological reactor.

Wastewater Treatment - Biodegradation of organic pollutants in municipal/industrial wastewater using aerobic/anaerobic bacteria.

Biopolymers - Continuous biosynthesis of commercially viable biopolymers like Polyhydroxyalkanoates (PHAs).

Recombinant Proteins - Therapeutic proteins, vaccines, industrial enzymes via microbial or mammalian cell culture biological reactor.

Renewable fuels - Biodiesel, bioethanol, butanol through fermentation of algal/microbial systems.

Scaling Up Bioprocesses

Careful scale-up is required to transfer laboratory-proven bioprocesses to larger, commercial-scale biological reactor. Strategies include:

Geometric Similitude - Maintaining constant power input per volume, kLa, shear rates across scales.

Dynamic Similarity - Matching dimensionless numbers like Reynolds at each scale.

Parallel Biological reactor - Test and validate processes through multiple, smaller units.

Fed-batch Operation - Incremental feeds to safely scale biomass, reduce inhibiting metabolites.

Continuous processing - Transition batch to continuous modes at commercial scales.

Mathematical Modeling - Scale-up guided by biokinetic and CFD models.

Advance Monitoring Techniques - Automation, sensors for precise control at large scale.

Challenges in Biological reactor

While biological reactor have revolutionized industrial biotech, certain challenges persist:

Foaming - Problematic foam formation increases with aeration, fluid mechanics complexity.

Scale-up - Transferring processes from laboratory scale to commercial-scale units remains difficult.

Contamination - Maintaining sterility across large volumes and prolonged operation periods.

By-product Inhibition - Metabolites/toxins at higher cell densities affects productivity.

Oxygen Transfer - Ensuring oxygen sufficiency across large working volumes.

Heat Transfer - Effective cooling at industrial scales with high biomass/metabolite loads.

Automation and Control - Developing advanced automation, control strategies for large units.

With further research and innovations, biological reactor will continue to be powerful production platforms for an expanding array of biomolecules, biofuels, and more. Careful bioprocess engineering will be essential for leveraging their potential at industrial scales. Overall, biological reactor represent one of the most transformative technologies enabling the modern biotechnology revolution.

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