Publish Your Research Online
Get Recognition - International Audience
Request for an Author Account | Login | Submit Article
|HOME||FAQ||TOP AUTHORS||FORUMS||PUBLISH ARTICLE|
Bioreactors - Classification and TypesBY: Sandhya Anand | Category: Applications | Submitted: 2011-04-06 17:33:19
Article Summary: "Bioreactors are designed to provide a controlled environment for optimal growth of microbes. The article describes the classification and types of bioreactors along with their advantages and disadvantages..."
Bioreactors are 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.
Classification of bioreactors
There are numerous types of bioreactors - batch, sequence, continuously stirred tanks, anaerobic contact processes, anaerobic filters, etc.
1. They can be conveniently classified into three major types based on the presence or absence of oxygen and requirement of stirring.
• Non stirred non aerated bioreactors are used for production of traditional products such as wine, beer, cheese etc.
• Non stirred aerated reactors are used much rarely.
• Stirred and aerated reactors are most often used for production of metabolites which require growth of microbes which require oxygen. Most of the newer methods are based on this type of bioreactors.
2. Based on mode of operation, the bioreactors can be classified into three types.
• Batch reactors
• Fed batch
• Continuous e.g.: chemo stat
3. Based on the method of growing of microbes, bioreactors can be either
• Suspended or
The Petri dish is the simplest immobilized bioreactor. The large scale immobilized bioreactors are used for commercial manufacturing of metabolites. They include
- Moving bed
- Fibrous bed
- Packed bed
4. On the basis of the microbial agent used, the bioreactors can be classified into
• Those based on living cells
• Which employ enzymes
5. Based on the process requirements, bioreactors can be classified into
c. Solid state
I. Aerobic fermentation
These reactors should have adequate provisions for supply of sterile air and also need a mechanism of stirring up and mixing the medium and cells. These can be either
a. Stirred tank or
b. Air lift type
Generally, they are either closed type or batch reactors. Some special cases use continuous flow reactors also.
1. Stirred tank bioreactor
This is the conventional mixing reactor which is made of either glass or stainless steel. The stirrer can be either at the top or bottom of the reactor. The dimensions of the reactor depend on the amount of heat to be removed from the vessel. Baffles in the centre of the tank prevent formation of vortex and effective mixing of the ingredients.
• Low investment needs
• Low operating costs
• Foaming is often a problem. But this can be overcome using proper antifoaming agents. However, this has to be exercised with caution since some antifoaming agents inhibit the growth of microbes.
2. Air lift bioreactors
The stirred tank bioreactors lack well defined flow of air. In these, air is pumped from below. This creates the bubbles in the medium which rises up through the draught tube by buoyancy and drags the surrounding fluid up. The air that is used to lift up is sufficient to stir up the contents.
• Low friction
• Less energy requirements
• The mechanical parts are easy to construct. There is no need of special aseptic seals.
• Scaling up is easier
• Metabolic performance does not drastically reduce on scale up.
• Capital needed is more
• Difficulty of sterilization
• Efficiency of mixing is low
II. Anaerobic fermentation
These reactors do not require aeration except in a few where initial preparation of inoculums requires aeration. Once the fermentation starts off, the gas released from the media is sufficient to provide mixing.
In case of enzyme production, the recovery has to be strictly under anaerobic conditions since for most of the enzymatic activity is sensitive to the presence of oxygen.
III. Immobilized cell bioreactors
These are based on immobilized cells.
• Useful fro manufacture of intracellular enzymes.
• When the extracted enzymes are unstable
• For preparing low weight products which are released into the medium.
• Reduction of pollution
• Allow continuous operation of bioreactors
• Suitable for production of amino acids, organic acids etc.
Commonly fluidized bed reactors and hollow fiber membrane bioreactors are used
1. Fluidized bed reactors
These reactors can utilize high density of particles and reduce bulk fluid density.
• Heat and mass transfer are efficient
• The mixing of the media between the liquid, solid and gaseous phases are effective.
• The reactor requires less energy.
• Low shear rates and hence suitable for cells which are more sensitive to friction like the plant cells and mammalian cells.
2. Hollow fiber membrane bioreactors
These reactors have hollow fibers are made from cellulose acetate, acrylic polymers, polysulphone etc.
• Extracellular products can be separated from cells at the same time.
• The productivity is high.
• Scale up is easy since several parallel fiber units can be added.
• Sometimes, the pores get plugged.
• Cell growth around the lumen can sometimes distort and rupture the fibers.
• Nutrients and products can diffuse through the membrane and limit the growth of microbes.
• If the toxic products happen to accumulate in the fiber it may inhibit the growth of microbes.
About Author / Additional Info:
Comments on this article: (8 comments so far)
• New Dimension of Scope and Career in Microbiology
• If You Feel Sluggish on a Daily Basis Here Are a Few Suggestions to Boost Energy
• Therapeutic Applications of Animal Venom
• Parallel Potential Prospects of Nanotechnology and Bioinformatics
Latest Articles in "Applications" category:
• Flavor Biotechnology: Part -1
• Flavor Biotechnology: Part -2
• Genetic Engineering Extended the Shelf-life of Fruits
• Biomedical Informatics - From Cells to Populations in the IT Way
• The Concept of Biotechnology: Understanding Various Applications/Uses
• In Vitro Fertilization Procedure - Applications, Advantages and Disadvantages
• Fluorescence-Activated Cell Sorting
• Directed Evolution
• Fermentation, and its Control
• Advanced Fermentation Control Strategies
• Methods of Purification of Enzymes
• Extremophilic Microbes - Organisms Living in Extreme Conditions
• Colorful Bacteria
• Importance of Phytoremediation
• Conservation of Microbes
• Sewage Bacteria - Strictly Anaerobic, Aerobic and Facultative bacteria
• Microbial Growth Substrates
• Injuries to Microbes
• Asepsis and its Importance
Important Disclaimer: All articles on this website are for general information only and is not a professional or experts advice. We do not own any responsibility for correctness or authenticity of the information presented in this article, or any loss or injury resulting from it. We do not endorse these articles, we are neither affiliated with the authors of these articles nor responsible for their content. Please see our disclaimer section for complete terms.
Copyright © 2010 biotecharticles.com - Do not copy articles from this website.
ARTICLE CATEGORIES :
| Disclaimer/Privacy/TOS | Submission Guidelines | Contact Us