Fermentation is a biological process where microorganisms (such as bacteria, yeast, or fungi) convert organic substances (like sugars) into different products, such as alcohol, acids, gases, or biomass.
It is widely used in food, pharmaceuticals, biotechnology, and biofuel production.
Fermentation can be categorized based on different criteria such as oxygen requirement, operational mode, and scale.
Based on Oxygen Requirement
1) Aerobic Fermentation
Requires oxygen.
Microorganisms use oxygen as an electron acceptor for metabolic processes.
Used in processes like antibiotic production (e.g., Penicillin), citric acid production, and vinegar production.
Requires proper aeration and stirring to supply oxygen efficiently.
2) Anaerobic Fermentation
Occurs in the absence of oxygen.
Microorganisms use alternative electron acceptors (like sulfate or nitrate).
Used in processes like ethanol production, lactic acid fermentation, and methane generation.
3) Facultative Fermentation
Microorganisms can grow in both aerobic and anaerobic conditions.
Example: Yeast (Saccharomyces cerevisiae) in ethanol production.
Based on Operational Mode
1) Batch Fermentation
All nutrients are added at the start, and no further addition occurs.
The culture grows, produces the desired product, and is then harvested.
Advantages: Simple, easy to control.
Disadvantages: Low productivity due to downtime for cleaning and setup.
Examples: Beer brewing, yogurt production.
2) Fed-Batch Fermentation
Fresh nutrients are added during the process without removing culture fluid.
Extends the growth phase and improves productivity.
Examples: Insulin production, antibiotic production.
3) Continuous Fermentation
Fresh media is continuously supplied, and the product is continuously harvested.
Advantages: High efficiency and productivity.
Disadvantages: Complex control and risk of contamination.
Examples: Biomass production (e.g., algae for biofuels).
4) Solid-State Fermentation (SSF)
Microorganisms grow on solid substrates without free-flowing liquid.
Examples: Mushroom cultivation, tempeh production.
5) Submerged Fermentation (SmF)
Microorganisms grow in a liquid medium.
Examples: Enzyme production (amylase, protease).
