Introduction

In the first half of the 20th century, ethyl alcohol and butyl alcohol were the most important
industrial fermentations in the world. Such products were vital to the synthesis of synthetic
rubber, especially during World War I. This required the development of bioreactors that could
culture thousands of liters. By the 1960’s, the fermentation of many simple organic products
diminished as chemical synthesis (mostly from petroleum) provided a cheaper alternative. It was
later discovered that the most efficient method of penicillin production occurred through
fermentation processes rather than using direct chemical synthesis. Hence the first large scale
manufacture of antibiotics occurred during World War II with the production of penicillin. Since
then, many other antibiotics have been characterized and mass-produced using fermentation.
Bioreactors and bacterial fermentation have played a vital role in the production of many
medicinal products including the majority of antibiotics.
The production of a particular bio product takes place through a sequence of steps forming the
biosynthesis of that product technology. The bioprocess has a common denominator, the
bioreactor, also called fermenter in which the biotechnological process is carried out and where
the biotic phase (biological agent) is placed in contact with the abiotic phase of the process.
Bioreactor is therefore a vessel designed specially to support the growth of living organisms that
are used in the production of useful bio products such pharmaceuticals, antibodies, vaccines, or
for the bioconversion of organic wastes. Majority of biotechnological processes are grouped into
three activities:

Upstream Bioprocess Downstream Product

processing itself processing

Biotechnology
Essential Components of a Bioreactor

Bioreactors are vessels used for carrying out biochemical processes which employ microbes,
fungus, plant cells or mammalian cell systems for production of biological products. The
bioreactors provide a controlled environment for the production of metabolites which can help
to achieve the optimal growth of microbes. The term fermentor is used as synonym to
bioreactors. There are various components of bioreactor which are important for any bioreactor
system;

Fermenter Vessel

• Material: Depending on the use and operating needs, bioreactor vessels are often
composed of plastic, glass, or stainless steel. Because of its strength, capacity to withstand
corrosion, and simplicity of cleaning and disinfection, stainless steel is the material of
choice.
• Size: Depending on the operational scale, bioreactors can range in size from laboratory-
scale vessels with a few liters to industrial-scale tanks with hundreds of liters or more.
• Design: The vessel's design affects elements like heat transport, oxygen transfer, and
mixing efficiency. Vases with spherical, conical, and cylindrical shapes are common; each
has a unique set of benefits for a particular use.

Agitation Systems

• Impellers
Impellers are revolving paddles or blades that stir up turbulence and encourage mixing
inside the bioreactor. Agitation systems usually come with them.
Depending on the necessary amount of agitation and the viscosity of the culture medium,
many types of impellers are utilized, including pitched blade turbines, Rushton turbines,
and marine impellers.
• Spargers
Devices called spargers are used to aerate culture media by adding air or oxygen.
 To facilitate effective gas-liquid interaction and oxygen transmission, they are made of
porous materials or diffusers placed at the bottom of the bioreactor.

Aeration Systems

• Aeration systems facilitate aerobic microbial growth and metabolism by introducing air or
oxygen into the culture media.
• Depending on the oxygen requirements of the microorganisms and the particular needs
of the bioprocess, either air or oxygen can be used.

Monitoring and Control Systems

• Sensor: Bioreactors are fitted with sensors to keep an eye on important variables including
temperature, pH, dissolved oxygen, speed of agitation, and concentration of substrate.
• Controllers: Control systems modify inputs including temperature, pH, agitation speed,
and aeration rate to control a number of factors inside the bioreactor.

Sterilization Systems

• Autoclaves: A lot of bioreactors are sterilized with autoclaves, which use pressure and heat
to remove microbiological contaminants from the growth media, vessel, and parts.
• Sterilization in Place: Steam-in-place (SIP) or chemical sterilization are examples of in-situ
sterilization techniques that may be used in larger industrial bioreactors.
Types of Bioreactors

The designs and configurations of bioreactors vary, and each is appropriate for a particular
purpose and set of operating parameters. Typical bioreactor kinds are listed below.

Stirred Tank Bioreactors

• Cylindrical containers having an impeller or other stirring gear to stir the contents are
called stirred tank bioreactors.
• For microbial fermentation and cell culture procedures, they are extensively utilized.
• Wastewater treatment, biotechnology, pharmaceuticals, and the food and beverage
sectors all use stirred tank bioreactors.

Air-lift Bioreactors
 • Gas or air injection is used in air-lift bioreactors to provide mixing and circulation inside
the vessel.
• They are made up of a draft tube that creates fluid circulation by raising gas bubbles.
• These bioreactors are frequently used for aerobic microbial cultures, which include the
synthesis of enzymes, biofuels, and antibiotics.

Packed Bed Bioreactors

• Microbial cells adhere to and develop on solid support materials like beads, pellets, or
fibers used in packed bed bioreactors.
• The packed bed allows the substrate solution to pass through, facilitating biological
processes.
• Wastewater treatment, bioconversion, and immobilized enzyme reactions are among
their applications.

Membrane Bioreactors

• The bioreactor system incorporates membrane filtering technology through membrane

bioreactors.
• For very effective wastewater treatment, they combine membrane separation with
biological treatment.
• Water reuse and environmental remediation are two common uses for these bioreactors
in municipal and industrial wastewater treatment facilities.

Photobioreactors

• Light is used in photobioreactors to power photosynthetic microorganisms like

cyanobacteria and algae.
• Their purpose is to enhance photosynthetic production and increase exposure to light.
• Biofuels, wastewater treatment, nutraceuticals, and biomass generation are among the
uses for them.
Based on mode of operation, the bioreactors can be classified into three types.
• Batch reactors
• Fed batch
• Continuous e.g.: chemo stat