Types of Fermenters Industrial Biochemistry

 

INDUSTRIAL BIOCHEMISTRY

Types of Fermenters

Biochemistry and Molecular Biology

Types of Fermenters

Fermenter

Fermenters are the vessels in which fermentation is carried out. They range from simple tanks to complex integrated systems.Types of Fermenters Industrial Biochemistry

Difference between Fermenter and Bioreactor

There is not as a such big difference between both the terms and the working principles are also very much alike regardless of the size and the type of device.

• Fermenters consist of a closed vessel, fitted with an air inlet and an agitator, in which the microbial or biochemical reaction occurs under controlled conditions for commercial purposes. Vessels that are used to grow microbial cells are often referred to as fermenters. They have a capacity of up to 2 liters.
• Those in which plants and mammalian cells grow are referred to as bioreactors. Bioreactors are large as compared to fermenters. Their size range from a few liters to cubic meters.

Types of Fermenters and Bioreactors

There are various types of fermenters and bioreactors based on the mode of operation, growth of microbes, and process requirement.

Mode of operation has three types:

1. Batch Fermenters
2. Fed-Batch Fermenters
3. Continuous Fermenters

The growth of microbes is divided into two types:

1. Suspended
2. Immobilized

According to process requirements, the following are the types:

1. Aerobic Fermenters
2. Anaerobic Fermenters
3. Solid state Fermenters
4. Immobilized Fermenters

Here, we will discuss different types of fermenters according to the process requirement and their subtypes further.

Aerobic Fermenters

In aerobic fermenters, an adequate supply of sterile air is required as well as a proper mechanism for stirring and mixing the medium of cells.

It has further two subtypes:

Stirred tank fermenter

Airlift type fermenter

Stirred Tank Fermenter

This microbial fermenter became famous in the 1940s after the production of life-saving antibiotics.

It performs the functions of homogenization; dispersion of gas-liquid mixtures, proper aeration of liquid and heat is also efficiently exchanged. The stirrer is present below or above the tank.

The conventional fermenter is carried out in batch mode with few modifications. These reactors are easy to operate and have a simple design. The industry still prefers batch mode because, in case of any contamination due to substandard items, the loss is minimal. However, it has the disadvantage of low productivity and nutrient concentration falls over time resulting in steady-state fermentation.

Recently, the fed-batch mode is also introduced to overcome these limitations. The tank provides an efficient stirring, reasonably good mass transfer, and at low cost, a variety of microbial species can be used. 

These fermenters are used for the production of hybridoma cells and monoclonal antibiotics.

Airlift type Fermenters

Airlift fermenters lack a well-defined flow of air. In these tanks, the air is pumped from below. This creates bubbles in the medium that will rise through the tube by using the principle of buoyancy and drags the surrounding fluid up. The air should be sufficient to stir up the contents and for lifting them up. Thus it is ideal for aerobic cultures. It can be used for free and immobilized both types of cells.

The riser tube has low density while the down-flow tube being less aerated has a higher density that causes the circulation of broth with the help of air. Oxygen is consumed and CO2 and other gases are produced in bulk. The efficiency of mixing could be low and sterilization difficulties.

Single Cell Protein (SCP)

 Air/ ammonia (gaseous) are introduced in the base of the riser tube while sterilized glucose, biotin, and minerals are pumped via down flow tube. SCP harvested is further processed.

Immobilized Cell Bioreactor

Fluidized Bed Reactors are an example of this bioreactor.

Recently designed reactors have three phases (solid, liquid, and gas) for cells and biocatalyst production. Utilize high density of particles.

It allows uniform mixing of particles, uniform temperature gradient, and the ability to operate reactions at a continuous rate.

Tower Fermenters

Bubble Column Tower FermenterIt is the simplest type of tower fermenter. Consists of glass and metal tubes in which air is introduced from the base. Used for citric acid and tetracycline production.

Vertical Tower Beer Fermenter

Designed for beer production and yeast biomass yield is enhanced. It contains a series of perforated tubes at different intervals. Also has a setting zone where yeast cells settle down and return to the main body of the fermenter and beer is removed as well.

Multistage Tower Fermenter

It consists of a column that is divided into compartments by placing perforated plates across the fermenter. The substrate is poured through the top and air is given from the base. Used for continuous culture of E-Coli, S-cerevisiae (baker’s yeast).

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Types of Fermenters Industrial Biochemistry