Lecture 5 (Bioprocess)

Bioprocess Overview

• Dr. Helena Stack, Munster Technological University

Microbial Growth and Product Formation

Bioprocess Definition

• Involves microbial growth and the formation of products.

Primary Metabolites

• Produced during the exponential phase of microbial growth.

• Integral to normal growth process.

• Includes:

  • Intermediates and end products of anabolic metabolism (e.g., amino acids, nucleotides).

  • Coenzymes (e.g., vitamins).

  • Examples: Citric acid, acetic acid, ethanol (from catabolic metabolism).

Secondary Metabolites

• Formed near the end of the growth phase (stationary phase).

• Have a significant impact on health and economics.

• Best-known example: Antibiotics.

• Other types include:

  • Pesticides, toxins, enzyme inhibitors, immunomodulating agents, antitumor agents, cholesterol-lowering agents.

What is a Bioprocess?

• An industrial biotechnology process using living cells for commercial product production.

• Types include:

  • Traditional bioprocesses.

  • Molecular biology (genetic engineering).

  • Laboratory and large-scale production optimization.

Stages of an Industrial Biotechnology Bioprocess

1. Upstream Bioprocess

   • Preparation of raw materials as food.

2. Fermentation and Transformation

   • Growth of microorganisms in a bioreactor.

3. Downstream Bioprocess

   • Purification of the desired product from the culture.

Upstream Process

Key Steps

• Identify product to produce and microorganism for production.

• Optimize growth conditions.

• Prepare inoculum and sterilize the bioreactor/media.

• Strain screening and improvement for high productivity.

Fermentation Process

• Microorganisms generate energy and products in the absence of oxygen.

Benefits of Fermentation

• Preserves food, enhances taste, aroma, and nutritional value.

• Preference for the term 'bioreactor' to accommodate aerobic and anaerobic processes.

Bioreactor Design Considerations

Factors Affecting Design

1. Oxygen Supply

   • Use of spargers and impellers to manage aerobic conditions.

   • Types of microorganisms include:

     • Strict aerobes, strict anaerobes, aerotolerant, facultative anaerobes, microaerophiles.

2. pH Regulation

   • Sensitivity to pH changes; adjustment of media based on metabolic activity.

3. Temperature Management

   • Sterilization and control systems to maintain optimal growth temperatures.

4. Nutrient Supply

   • Simple nutrient requirements compared to plants/animals.

   • Macro and micronutrient balance for optimal growth.

Downstream Process

• Involves extraction and purification of products.

Steps

1. Isolation

   • Mechanical cell disruption and removal of insolubles.

2. Extraction

   • Filtration, centrifugation.

3. Purification

   • Membrane filtration and chromatography.

4. Finishing

   • Drying and sterilization processes.

Types of Bioreactors

Stirred-tank and Batch Fermentation

• Cyclical processes involving:

  1. Addition of sterile feed and inoculum.

  2. Growth and production phases.

  3. Cleaning and maintenance between cycles.

Monitoring Bioprocess

• Achieved through sensor technology for pH, foam detection, and product sampling.

Continuous Culture

• Characteristics include constant nutrient replenishment and media removal, maintaining steady-state growth without stationary phase.

Advantages of Continuous Culture

• Efficient product harvesting, reduced downtime, and long-term operation capabilities.

Disadvantages

• Risks of contamination, mutation, and wash-out effects leading to production decline.

Conclusion

• Successful bioprocessing depends on understanding microbial behavior, optimizing growth conditions, and managing physical parameters in bioreactors for efficient product formation.