Fermentation Technology: Meaning, Types and FAQs

Table of Contents

• Introduction to Fermentation
• Background of Fermentation
• Types of Fermentation
• Solid State Fermentation (SSF)
• Submerged Fermentation (SmF)
• Batch Mode
• Fed-batch Mode
• Continuous Mode:
• Types of Fermenter
• Application of Fermentation in Biotechnology
• Frequently Asked Questions

Introduction to Fermentation

Fermentation technology is a field which utilises microorganisms and enzymes to produce compounds that find use in pharmaceutical, chemical, energy, material and food industries. Biotechnology can be defined as the amalgamation of natural sciences and engineering techniques to utilise organisms, cells and their parts for industrial products and services. Thus, fermentation is a biotechnological tool that uses microorganisms to produce several industrial products.

Fermentation is a very ancient technique that has been in use for thousands of years. It was used for the first time in the production of beer. Today, biotechnology has intersected with fermentation technology to create value-added products such as hormones, enzymes, antibiotics and other metabolites.

Background of Fermentation

Louis Pasteur was the first scientist to study fermentation back in the middle of the 19th century. He showed that living cells like yeast could demonstrate fermentation. He also showed the process of lactic acid fermentation in living cells.

Later in 1907, Eduard Buchner bagged a Nobel Prize for demonstrating the process of fermentation in yeast cells. In 1929, another pair of scientists, namely Arthur Harden and Hans Euler-Chelpin, won a Nobel Prize for their investigation of how enzymes cause fermentation. By the 1940s, the production of antibiotics by fermentation was established.

Fermenters were first developed by a British scientist, Chain Weizmann, for the production of acetone in WW1. However, first, large-scale fermenters were developed in 1944 for the production of yeast. Finally, an industrial level fermenter with aseptic conditions, good agitation and aeration was developed by Hindustan Antibiotic Ltd., Pimpri, Pune, in 1950 in India.

Types of Fermentation

1. Solid State Fermentation (SSF)

Solid state fermentation is the growth of microorganisms on a moist solid substrate in the absence or minimum water between the particles. The moisture content of the solid medium is between 12-80%. This type of fermentation is largely used for agricultural products and foods, such as soybean by Aspergillus and Rhizopus.

The six different types of solid state fermenters used are: (i) Rotary drum, (ii) Tray, (iii) Swing solid state, (iv) Packed-bed, (v) Air-solid and (vi) Stirred vessel.

The application of SSF includes:

• Enzyme production such as pectinase, cellulase, protease, amylase and phytase.
• Production of organic acids such as gallic acid and lactic acid.
• Various secondary metabolites can be produced by SSF, such as gibberellic acid and antibiotics.
• Production of unsaturated fatty acids and biocontrol agents.

The advantages of SSF include high product titre, low use and waste of water, no hassle of foaming, low expenditure and reduced energy requirements. There are, however, several disadvantages of SSF, such as difficulty in controlling moisture of the solid substrate, poor oxygen availability, no method to control pH during fermentation, and only limited species that can be used in SSF.

2. Submerged Fermentation (SmF)

Submerged fermentation involves the cultivation of microorganisms in an enriched liquid broth. This type of fermentation is mainly employed for industrial applications. This procedure involves growing a microbe in a closed container containing broth rich in nutrients with high levels of oxygen. The production medium is an important component of the submerged fermentation that is optimised according to the microbe and target molecule.

There are three modes in which SmF is carried out: (i) Batch mode, (ii) Fed-batch mode and (iii) Continuous mode. Let us look at them in detail.

a. Batch Mode

It is a simple mode of fermentation where all the prerequisites for the process are added in a container, and nothing is added in between except air. The prerequisites include sterilisation of the fermenter and production medium and addition of inoculum. The fermenter is run in a closed manner, and the process is terminated when either the nutrient is exhausted or the target molecule has reached its maximum concentration.

Advantages of batch mode include:

• Simple to use.
• Less chances of contamination.
• It can be handled by a relatively inexperienced operator.

b. Fed-batch Mode

As the name suggests, the fed-batch mode is a type of fermentation where the system is not run in a closed manner. In this mode, substrates, nutrients, or inducers are added to the system when required. This addition of products increases the productive phase of the microorganism.

Advantages of fed-batch fermentation are:

• High cell density is achieved.
• It leads to increased production of metabolites.
• The growth rate of the organism and its oxygen requirement can be controlled.

c. Continuous Mode

In this mode, the organism is fed with fresh nutrients along with the removal of spent medium and cells so as to maintain the volume, substrate concentration, product and biomass at a constant rate.

Advantages of continuous mode include:

• It gives a longer period of productivity.
• The high density of cells is achieved.
• Culture physiology can be studied in this mode.

Types of Fermenter

There are six types of fermenters or bioreactors that are used in industries. They include:

1. Continuous stirred tank fermentor
2. Airlift fermentor
3. Bubble column fermenter
4. Fluidised bed fermenter
5. Packed bed fermenter
6. Photo bioreactor

Application of Fermentation in Biotechnology

Fermentation technology is widely being used in various industrial products, such as:

1. Production of cells or biomass: The fermentation process involves producing the cells in a large amount that can be used for the extraction of metabolites. When an inoculum of microorganisms is grown in a properly enriched production medium, it reaches its maximum growth rate. The biomass obtained can be downstream to extract the target product.
2. Production of metabolites: Fermentation technology is used to produce both primary and derived metabolites from microorganisms. Primary metabolites are produced in the growth phase of the microorganism, and examples include ethanol, citric acid, tryptophan, lysine and threonine.

Secondary metabolites are produced by microorganisms during the stationary phase of their life cycle. Examples of secondary metabolites include antibiotics like penicillin and bacteriocins.

3. Modification of compounds: Fermentation technology can be applied to alter the metabolic pathways using cultivation-based or molecular approaches.
4. Production of recombinant products: Recombinant proteins, vaccines and hormones can be produced by fermentation that are used widely by pharmaceutical companies.

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Also Read:

• MCQs on Fermentation Process for NEET
• Difference between Batch and Continuous Fermentation