B.Sc. Final (Biotechnology)

Assistant Professor Shubham Shukla
Department of Microbiology
Fermentation

Types of Fermentation

1. Based on Oxygen Requirement

A. Aerobic Fermentation

• Requires oxygen
• Microorganisms: Aspergillus, Penicillium, Bacillus
• Products:
• Enzymes (amylase, protease)
• Organic acids (citric acid)
• Antibiotics
• Example: Citric acid production by Aspergillus niger

B. Anaerobic Fermentation

• Occurs in absence of oxygen
• Microorganisms: Saccharomyces cerevisiae, Clostridium
• Products:
• Alcohol
• Organic solvents
• Biogas
• Example: Ethanol production by yeast

2. Based on Product Formation

A. Alcoholic Fermentation

• Reaction: Sugar → Ethanol + CO₂
• Microorganism: Saccharomyces cerevisiae
• Application: Brewing and winemaking

B. Lactic Acid Fermentation

• Reaction: Sugar → Lactic acid
• Microorganisms:
• Lactobacillus (homofermentative)
• Leuconostoc (heterofermentative)
• Application: Curd, yogurt, cheese

C. Acetic Acid Fermentation

• Reaction: Alcohol → Acetic acid
• Microorganism: Acetobacter aceti
• Application: Vinegar production

D. Butyric Acid Fermentation

• Reaction: Sugar → Butyric acid
• Microorganism: Clostridium butyricum

3. Based on Physical State of Medium

A. Submerged Fermentation (SmF)

• Microorganisms grow in liquid medium
• Requires aeration and agitation
• Products: Antibiotics, enzymes, vitamins
• Advantages: Easy control, uniform conditions

B. Solid State Fermentation (SSF)

• Growth on moist solid substrate without free water
• Microorganisms: Fungi (Aspergillus, Rhizopus)
• Products: Enzymes, traditional foods (tempeh)
• Advantages: Low cost, high product concentration

4. Based on Process Operation

A. Batch Fermentation

• Medium and inoculum added at start
• No addition or removal during process
• Simple and commonly used

B. Fed-Batch Fermentation

• Nutrients added periodically
• Prevents substrate inhibition
• Application: Antibiotics and enzymes

C. Continuous Fermentation

• Continuous addition of medium and removal of product
• Steady-state operation
• Advantage: High productivity
• Risk: Contamination